I think I've quit 2 bands by my own choice, and a couple were other people moved away and the activity just naturally fizzled out. Latest was probably the biggest happening (in 2021) as it was a band I had stayed with for 14 years and used to always prioritize over other projects. Even though we had the band going for that long (and a big array of member changes, mainly vocalists and lead guitar players) we were never really a big success, we made some albums (self founded), got some radio play, played some concerts each year (allthough we usually had to work hard to get them) and paid for a spot on some european tours. I always felt the style was very limited for me, a type of melodic death metal (In Flames, At The Gates type) with some groove/thrash elements. But the riffs were usually really stale in my opinion, and usually always the same song structures, it didn't really lend itself to great creative outlet. I don't know, it was a good feel for the first years, then we stuck around mostly because we became good friends and had fun together, in my opinion. But when I had another project which I felt clicked more with my style and gigs with that band really just fell in our lap naturally, basically no work involved, I made the decision to quit (along with the original guitarist who also contemplated doing it), very sad and felt like I just broke up with a girlfriend I stayed with for a long time. But also having children and less time/money available, it was hard balancing two bands that both wanted to gig and record albums, mostly self funded... Not to mention travelling one hour just for practice, in both bands...
Other than that I quit a party cover band as I had 3 bands at that time, and it just became too much to handle.
I never got fired though, *knock on wood*.