They have a bad habit of trying to force standards through the W3C without thinking through what they're doing, they're really bad at responding to bug reports or engaging with devs, they regularly introduce breaking changes to existing web content without giving user overrides. The recent audio changes are a good example of just how broken their dev process is[0].
Firefox is still Firefox, they're fine. The Edge team honestly is pretty great too. Working with Chrome devs as a web developer kind of stinks, and I think it's partially because they're so dominant and they just don't have to care.
Especially on mobile, if you're even remotely a power user Firefox is just flat-out a better Android browser since it supports extensions.