I've been wondering that myself. I've only entered my pw into Jerboa, which is made by the Lemmy devs (and Liftoff once, but changed the pw since).
Now I only ever use FOSS apps, which all seem to be under some amount of scrutiny, but idk how much is enough.
I've always been particularly wary of Voyager/wefwef. Not that I wouldn't trust the devs, but the whole concept of entering a password into a 3rd page that only passes it onto the right page, damn that's just dumb on principle.
It's particularly weird since this is home for so many techies and privacy/security advocates.