helo!!! I found this one:
Prime Minister in Disguise Webtoon
https://www.mangago.zone/read-manga/prime_minister_in_disguise/
I'm not sure about the specifics on why the MC was forced to pretend to be a woman (I actually know anoter one thats similar but I doubt its that one - I'll link it here if I manage to find it) but in this story the MC used to be a general, he started crossdressing as a scheme to get back at the Emperor for disrespecting his sister (him and his sister look alike) lmao. Lemme know <3
I found the other, unserious one (trust me its not this one, its so funny tho)
Don’t Touch Me You Gay Emperor!
https://www.mangago.zone/read-manga/don_t_touch_me_you_gay_emperor/
I didn't get an answer, so I don't know if it's the manhwa they were talking about, but I'll check it out.
Someone on Reddit searched for bl manhwa and the description sounded interesting and now I want to read it too. Does anyone know what it is?
He described it this way:
"I'm looking for a bl historical Manwha, where the MC used to be a general but is now forced to pretend/become a women or something like that. I can't remember please help me find it."