I love this one, it's so bitter and interesting https://www.mangago.zone/read-manga/gozen_2ji_made_kimi_no_mono/
Some others:
https://www.mangago.zone/read-manga/tasogare_dare/
https://www.mangago.zone/read-manga/the_actor_wants_to_divorce/
https://www.mangago.zone/read-manga/kokuhaku_no_jikan/ (this might not be amnesia, memory is a bit fuzzy)
https://www.mangago.zone/read-manga/boku_no_naka_ni_kimi_ga_inai/
https://www.mangago.zone/read-manga/mr_fiction/
https://www.mangago.zone/read-manga/warui_otona_ni_narimashite/
https://www.mangago.zone/read-manga/mou_ichido_nando_demo/
Do check the tags https://www.mangago.zone/tag/amnesia/ and https://www.mangago.zone/tag/memory%20loss/
Placebo Memories.
Ways of Parting (this has angst).
wanna read some bl with mc/ml loss their memories even angst is ok(๑•ㅂ•)و✧