In The "Lyings" of a Woman: Male-Male Incest in Leviticus 18.22? K. Lings argues the original meaning was, while hard to translate, something akin to

Lying with a close male relative is just as detestable as lying with a close female relative.

Ie. this is also a prohibition against incest as so many prohibitions of this chapter are.

In The "Lyings" of a Woman: Male-Male Incest in Leviticus 18.22?, a philological/literary analysis of Lev 18.22:

If the text is analysed and translated carefully, there are reasons to believe that Lev. 18.22 is proscribing incest between male family members.

the paper argues the original meaning was, while hard to translate, something akin to

(a) You shall not lie with close relatives, whether male or female.
(b) With a male relative you shall not engage in sexual relationships prohibited with female relatives.