BL with a Seinen vibe?

https://www.mangago.zone/read-manga/hikaru_ga_shinda_natsu/
https://www.mangago.zone/read-manga/yuki_to_matsu/
https://www.mangago.zone/read-manga/madk/
Also its only at its first chapter but Kegare no Nai Hito has a pretty dark premise.

https://www.mangago.zone/read-manga/coyote_zariya_ranmaru/
https://www.mangago.zone/read-manga/canis/
https://www.mangago.zone/read-manga/gift_ichinose_yuma/
https://www.mangago.zone/read-manga/stigmata_seikon_sousa/
I recommend u try these out if u haven't alr :)

This one is my frvt nowdays actors + struggle + bl in subtext -
https://www.mangago.zone/read-manga/double_noda_ayako/

These are the mangakas you can read any of their works if you’re looking for BL with seinen vibes : Takahashi Hidebu, Zarya, Okadaya Tetuzoh.

- Twittering Birds Never Fly
https://www.mangago.zone/read-manga/saezuru_tori_wa_habatakanai/

- Canis
https://www.mangago.zone/read-manga/canis/

- Acid Town
https://www.mangago.zone/read-manga/acid_town/

- Hikaru Ga Shinda Natsu (Seinen + BL)
https://www.mangago.zone/read-manga/hikaru_ga_shinda_natsu/

- Midnight Rain
https://www.mangago.zone/read-manga/midnight_rain_ctk/

- I Need to Suck Blood Tonight
https://www.mangago.zone/read-manga/yabun_ni_kyuuketsu_shitsureishimasu/

- Darkness Before The Dawn
https://www.mangago.zone/read-manga/darkness_before_the_dawn/

- Staring At Your Back (seinen+ BL)
https://www.mangago.zone/read-manga/staring_at_your_back/