There's this one called "The fallen duke and the knight who hates him." (I think i got the title right) so far it's shounen ai i guess
It isn't exactly regression, but these are like Kill The Lights:
-Modern school environment.
https://www.mangago.zone/read-manga/geu_kkeute_issneun_geos/
-Manhua like 2ha
https://www.mangago.zone/read-manga/mo_dao_zu_shi_novel/
-Manhua with an element of regression, but it's mostly revenge. It's also Mpreg. It's also long as fuck.
https://www.mangago.zone/read-manga/deliverance_of_the_counterattack/
This one is regression, but it's literally just smut. Short and hot.
https://www.mangago.zone/read-manga/beta_count_so_has_changed/
Hop you find something to read!
BL Regression manhua/manga/manhwa recs? I’ve read Turning, 2ha, Palace if Bardo, and Kill the Lights