The internal evidence for Lazarus as the “beloved disciple” is so strong that even conservative New Testament scholar Ben Witherington supports this interpretation of the figure’s identity. In “Was Lazarus the Beloved Disciple?,” Witherington explains:
It has been common in Johannine commentaries to suggest that the Beloved Disciple as a figure in the narrative does not show up under that title before John 13. While this case has been argued thoroughly, it overlooks something very important. This Gospel was written in an oral culture for use with non-Christians as a sort of teaching tool to lead them to faith. It was not intended to be handed out as a tract to the non-believer but nevertheless its stories were meant to be used orally for evangelism. In an oral document of this sort, the ordering of things is especially important. Figures once introduced into the narrative by name and title or name and identifying phrase may thereafter be only identified by one or the other since economy of words is at a premium when one is writing a document of this size on a piece of papyrus (Jn. 20.30-31). This brings us to John 11.3 and the phrase hon phileis [‘the one whom you love’]. It is perfectly clear from a comparison of 11.1 and 3 that the sick person in question first called Lazarus of Bethany and then called ‘the one whom you love’ is the same person as in the context the mention of sickness in each verse makes this identification certain. This is the first time in this entire Gospel that any particular person is said to have been loved by Jesus. Indeed one could argue that this is the only named person in the whole Gospel about whom this is specifically said directly. This brings us to Jn. 13.23.
At John 13.23 we have the by now very familiar reference to a disciple whom Jesus loved (hon agapa this time) as reclining on the bosom of Jesus, by which is meant he is reclining on the same couch as Jesus. The disciple is not named here, and notice that nowhere in John 13 is it said that this meal transpired in Jerusalem. It could just as well have transpired in the nearby town of Bethany and this need not even be an account of the Passover meal. Jn. 13.1 in fact says it was a meal that transpired before the Passover meal. This brings us to a crucial juncture in this discussion. In Jn. 11 there was a reference to a beloved disciple named Lazarus. In Jn. 12 there was a mention of a meal at the house of Lazarus. If someone was hearing these tales in this order without access to the Synoptic Gospels it would be natural to conclude that the person reclining with Jesus in Jn. 13 was Lazarus. There is another good reason to do so as well. It was the custom in this sort of dining that the host would recline with or next to the chief guest. The story as we have it told in Jn. 13 likely implies that the Beloved Disciple is the host then. But this in turn means he must have a house in the vicinity of Jerusalem. This in turn probably eliminates all the Galilean disciples.
Notably, Witherington interprets Lazarus as a historical person who authored John (which he argues was later edited by John of Patmos), whereas this article favors the view that the role of Lazarus in John is probably based on a redaction of an allegorical Lazarus in Luke 16:20-31. Given this possibility, it is untenable that the Lazarus described in John was actually a historical person, rather than just an allegorical character or literary invention.
Witherington also notes a number of other problems with the tradition that John the son of Zebedee authored the fourth gospel:
One of the things which is probably fatal to the theory that John son of Zebedee is the Beloved Disciple and also the author of this entire document is that none, and I do mean none, of the special Zebedee stories are included in the Fourth Gospel (e.g., the calling of the Zebedees by Jesus, their presence with Jesus in the house where Jesus raised Jairus’ daughter, the story of the Transfiguration, and also of the special request for special seats in Jesus’ kingdom when it comes, and we could go on). In view of the fact that this Gospel places some stress on the role of eyewitness testimony (see especially Jn. 19-21) it is passing strange that these stories would be omitted if this Gospel was by John of Zebedee, or even if he was its primary source. It is equally strange that the Zebedees are so briefly mentioned in this Gospel as such (see Jn. 21.2) and John is never equated with the Beloved Disciple even in the appendix in John 21 (cf. vs. 2 and 7— the Beloved Disciple could certainly be one of the two unnamed disciples mentioned in vs. 2).
Other proposed candidates for the author of the fourth gospel include John the Presbyter, John Mark, and Thomas. Regardless, even Christian scholar Raymond Brown (An Introduction to the New Testament, pp. 368-369) explains, “As with the other Gospels it is doubted by most scholars that this Gospel was written by an eyewitness of the public ministry of Jesus.” What is further noteworthy is that even many conservative New Testament scholars doubt the traditional authorship of John. Ben Witherington identifies Lazarus as the intended author of the text (discussed in endnote 30 above), and Martin Hengel and Richard Bauckham have proposed John the Presbyter, in place of John the son of Zebedee.
It should also be noted that Mark Goodacre (“NT Pod 38: Who is the Beloved Disciple in John’s Gospel?“), who does think that the author of the fourth gospel is trying to suggest that the beloved disciple is John the son of Zebedee, still does not think that this John authored the gospel (https://podacre.blogspot.com/2010/06/nt-pod-38-who-is-beloved-disciple-in.html). Goodacre notes how the entire use of the beloved disciple in the Gospel of John is highly ambivalent, and how this likely reflects the fact that even the narrator of the text is not making an overt authorial attribution. Another possible explanation of why the beloved disciple’s identity is kept anonymous is because the text is not referring to a historical figure at all, but instead is using the beloved disciple as a fictive narrative device that makes him the ideal witness for Christian readers to emulate.
It is not clear that the “beloved disciple” described at the end of John is even intended to be understood as the author of the work. As scholar Robert Kysar (The Anchor Bible Dictionary, v. 3, pp. 919-920) explains, “The supposition that the author was one and the same with the beloved disciple is often advanced as a means of insuring that the evangelist did witness Jesus’ ministry. Two other passages are advanced as evidence of the same—19:35 and 21:24. But both falter under close scrutiny. 19:35 does not claim that the author was the one who witnessed the scene but only that the scene is related on the sound basis of eyewitness. 21:24 is part of the appendix of the gospel and should not be assumed to have come from the same hand as that responsible for the body of the gospel. Neither of these passages, therefore, persuades many Johannine scholars that the author claims eyewitness status.”
Likewise, while church tradition maintains that John the son of Zebedee lived to a very old age, there is also a body of ancient evidence indicating that he died much earlier, being executed alongside his brother James, whose martyrdom is described in Acts 12:2. This body of evidence indicating that John did not live to old age is laid out by scholar F.P. Badham in “The Martyrdom of John the Apostle.” Likewise, even conservative New Testament scholar Ben Witherington (“Was Lazarus the Beloved Disciple?”) explains:
Papias Fragment 10.17 has now been subjected to detailed analysis by M. Oberweis (NovT 38 1996), and Oberweis, rightly in my judgment draws the conclusion that Papias claimed that John son of Zebedee died early as a martyr like his brother (Acts 12.2). This counts against both the theory that John of Patmos was John of Zebedee and the theory that the latter wrote the Fourth Gospel.

While it is historically uncertain whether John died alongside James, this body of evidence casts doubt on the tradition that John lived to an old age and thus raises further problems for the notion that John authored the fourth and latest gospel. As I explain in my essay “March to Martyrdom,” our evidence for any of these church figures is very, very limited. In light of such problematic evidence, in addition to contradictions among our sources, it is not tenable that John the son of Zebedee ever lived to an old enough age to author the gospel later attributed to him. This is just another problem for the authorial tradition of the fourth gospel, in addition to the numerous other ones listed above.
Sometimes apologists cite Irenaeus’ letter to Florinus (Eusibius Historia Ecclesiastica 5.20) as evidence that he knew, on the basis of good authority, that John the disciple authored the fourth gospel. However, this argument is based largely on speculation. In the letter, Irenaeus states that he knew Polycarp as a child. He also states that Polycarp was a companion of John the disciple. The logic goes that, since Polycarp knew John, he must have told Irenaeus (when he was a kid) that John authored the gospel attributed to his name. However, as scholar R. Alan Culpepper (John, the Son of Zebedee: The Life of a Legend, p. 126) explains, “In this excerpt from the letter, Irenaeus reminds Florinus of their common experience, sitting at the feet of Polycarp. His point is to remind Florinus that he did not learn his Gnostic views from Polycarp … On the other hand, Irenaeus does not say that Polycarp taught that the apostle John was the author of the Fourth Gospel, the Epistles, or Revelation.”
That being said, it has been argued by David Trobisch (“Who Published the New Testament?,” p. 33) that Polycarp may have been responsible for the publication of the first edition of the New Testament. Trobisch acknowledges, however, that this argument is based on probability and not certainty. Trobisch’s broader thesis is that the church in Asia Minor, during the mid-2nd century CE, had a strong influence over the selection of the canonical books. Since Polycarp was an authoritative figure in this region and during the same time period, Trobisch suggests that he may have been the one who selected the names of the Gospel titles, along with the other books of the New Testament. There is a catch, however: Trobisch also argues that the names of the Gospels were selected on the basis of internal passages within the New Testament, as discussed in endnote 26 above. As such, Polycarp would have more likely chosen the names as part of an editorial process, linking the books together, rather than on the basis of personal knowledge that he had of the disciples.
There are also major problems for assuming that Polycarp personally knew John the son of Zebedee. There is a body of ancient evidence suggesting the John died alongside his brother James in 44 CE. Polycarp likewise did not write anything that we can date with certainty prior to c. 110-140 CE. This creates a rather problematic chronology, if the traditions implying an early death of the disciple John are accurate. But it should likewise be noted that, even if John had not been martyred with James, it is still doubtful that he lived and traveled long enough to know Polycarp, who was active in Asia Minor around the mid-2nd century. The sources claiming that John the son of Zebedee traveled to Ephesus (e.g., the Acts of John), and lived to a very old age, are primarily based on later traditions intended to grant special importance and authority to the church at Ephesus. Our sources for what happened to any of the apostles, after the Book of Acts, are highly problematic, and full of legendary (and often contradictory) information. This situation likewise applies to John the son of Zebedee. Polycarp also does not state in his own writing that he knew or traveled with John or any of the apostles. Irenaeus mentions this detail, but it is likely to aggrandize Polycarp.
Why then was Polycarp associated with John? A far more likely explanation is that he actually knew John the Presbyter. As discussed by New Testament scholar James McGrath in “Which John? The Elder, the Seer, and the Apostle,” there were several figures named “John” in the early church, whose identities became conflated in the 2nd century and onward, including during the time of Irenaeus. What is very likely the case, therefore, is that Polycarp knew a leading authority named “John,” who was later conflated with the disciple John the son of Zebedee. This conflation likewise happened with Papias, as Michael Kok discusses under the “External Evidence” section above. Since Papias only knew John the Presbyter, or “elder John,” it is likewise probable that Polycarp only knew this figure, as well. And, if that’s the case, it would also explain where Polycarp got the names “Matthew” and “Mark” for the first and second gospels, since these authorial traditions, as Kok explains, derive from John the Presbyter (who likewise, at least in the case of Mark, appears to have derived the name from internal references within other books of the New Testament). In such a case, Polycarp would have only repeated the dubious Papian tradition for the authorship of Matthew and Mark, discussed above, when he assembled the New Testament canon.

As noted, Trobisch’s argument that Polycarp assembled the canon is purely probabilistic. It should also be noted that Polycarp does not refer to the Gospels by their traditional names in his own writing (see here), which is part of the evidence (in addition to other anonymous quotations among the early church fathers) that the Gospels had not yet been given their traditional titles by the mid-second century CE (discussed further in endnote 20 above). Even if Polycarp was responsible for adding the titles after this date, therefore, he still provides evidence that the titular affixation did not take place until the late-2nd century.

https://www.youtube.com/watch?v=71mX31Tn5-k&ab_channel=BartD.Ehrman