Look at the head of this chapter: “And Yahweh said to Moses, ‘Say to the priests, the sons of Aaron. . .’” In other words, this specific chapter was meant exclusively for the Aaronid priesthood, and besides, the only man that could offer bread to Yahweh was the Aaronid priest (Ex 25:30). Chapters 21-22 might have existed, like Lev 1-7, as a once independent text for the Aaronid priesthood exclusively.
More generally on the authorship and this excerpt from a PhD professor:
Throughout the book of Leviticus, and especially in those chapters devoted to its laws and commandments (Lev 11-22), the role of the Aaronid priests is repeatedly defined by the phrase “to distinguish between the holy and the profane, between the pure and the impure.” In fact, the whole priestly law code is presented as the very instruction (torah) for doing this. Its torahs are “to distinguish between the holy and the profane, the pure and the impure” in matters of: diet (Lev 11); women, i.e., menstruation and childbirth (Lev 12); skin diseases and afflictions (Lev 13-14); bodily emissions (Lev 15); sex and nudity (Lev 18, 20); miscellaneous matters (Lev 19); and issues concerning the Aaronid priesthood (Lev 21-22).

Thus according to the priests who composed this text, certain foods are unclean or impure; a woman’s menstruation is impure; any bodily discharge or emission is impure; leprosy and other skin infections are impure; in fact diseases by their very nature are impure; any clothes or a house that comes into contact with the infectious is also unclean and impure. Anything that touches, for example, pork, a corpse, the blood of a menstruating woman—whether a bottle, a piece of clothing, a bed, the walls of your house, etc.—also becomes contaminated and impure and must be purified through washing or simply discarded. Likewise, any individual coming into physical contact with a corpse or the blood of a menstruating woman also becomes impure. Exposing the nudity of one’s relative is impure; homosexuality is impure; having intercourse with a menstruating woman is unclean; mix-breeding animals and different kinds of seeds are impure; eating a torn animal is impure, and so on. Moreover, any individual who has contracted an impurity (i.e., committed a sin) and does not expiate his impurity/sin through a ritualized washing and sacrifice officiated over by the Aaronid priest was irrevocably cut off and banished from the community.
There are numerous other examples of pro-Aaronid legislation and a pro-Aaronid Yahweh that are only found in the Priestly source—all of which stand in sharp contrast to the pan-Levite legislation and pan-Levite Yahweh of Deuteronomy. Thus, in this Aaronid-written text, and only in this text, do we find “Yahweh” endorsing:
the sole selection of the Aaronids as his priests and the demotion of all other non-Aaronid Levites as their servants [Exod 28:1-4, 41-43; 29:1-9; 40:13-15; Lev 7:35-36; Num 3:5-10; 8:18-19 (contra Deut 18:1-5; 17:9, 18; 24:8; 27:9; 33:8-10)];

the sole right of the Aaronids to officiate sacrifices; and therefore the sole right of the Aaronids alone to expiate and atone for sin [Lev 1-7, and the book of Leviticus in general. See also Num 15 (contra Deut 18:1-5)];

the sole right of the Aaronids to enter the Tabernacle [Num 1:51; 3:10, 38; 18:5-7, 22];

the sole right of the Aaronids alone to touch Yahweh’s holy objects [Num 4:1-19 (contra Deut 18:1-8; cf. 1 Sam 6:13-19)];

the sole selection of Aaronid priests as judges [Exod 28:30; Lev 13; Num 5:16-28 (contra Deut 17:8-13; 33:8-10)];

the sole right of the Aaronids to be able to eat Yahweh’s sacrifices [Lev 6:9-11, 19-22; 10:12-15 (contra Deut 18:1-2)];

the sole right of the Aaronids as the beneficiaries of the people’s firstfruit offerings and donations [Num 18:8-14; Lev 6-7];

and the sole right and privilege of the Aaronids to burn incense [Exod 30:7; Num 17:5 (contra Deut 33:10)].
Overall:
All of these Yahweh-decreed pro-Aaronid privileges are only found, not surprisingly, in this text written by priests who traced their lineage back to Aaron.

Additionally, all the privileges enjoyed by the Aaronid priests and their function as Yahweh’s sole ministers were also legitimated through divine decree by presenting them as “Yahweh’s eternal laws.” In other words, the Aaronid priestly guild responsible for the composition of this scroll has Yahweh decree all of the following as “eternal law”: the anointing of the Aaronids as Yahweh’s sole priests (Exod 28:1-4, 41-43; 29:9; 40:12-15; Lev 6:15; Num 10:8); the daily lamp that must be kept lit by the Aaronid priests (Exod 27:20-27; Lev 24:3, 9); Yahweh’s show bread which must be displayed daily by the Aaronids (Exod 25:30); the Aaronid priesthood’s portion of the sacrifices (Exod 29:28; Lev 6:11; 7:34; 10:15; 24:9); the daily sacrifice and continual fire on the altar (Exod 29:30; Lev 6:6); the washing of the Aaronid priests before they enter the Tabernacle (Exod 30:21); the prohibition of beer and wine for Aaronids before entering Yahweh’s presence (Lev 10:9); and all donations, firstfruits, and sacrificial offerings belong eternally to Aaron and his sons (Num 18:8, 11, 19). In other words, the whole care and legitimation of the Aaronid priesthood and the sacrificial cult as envisioned and officiated over by the Aaronid priests themselves are repeatedly highlighted as “Yahweh’s eternal laws” throughout the very text that they themselves wrote! Moreover, these eternal decrees occur nowhere else in the Bible but in this text, the Priestly scroll. [fn. One may find sympathetic decrees in the fourth century books of Chronicles, which also display the concerns of an Aaronid author, and the book of Ezekiel, which was apparently written by an Aaronid Zadokite priest.]
Again for readers unfamiliar with ancient Near Eastern literature—and that is most “readers” of the Bible—this is precisely what ancient literature did and was composed to do. Properly we would label this as propaganda—that is literature written to endorse and in this case divinely authenticate the sole authority, ideology, and beliefs of its authors.