I've been using FF for more years than I care to remember, and with the exception of a couple of sites that weren't really that important, I've never had an issue. I certainly never had an issue running uBlock Origin and YouTube.

I flat out refuse to use anything even loosely based on Chromium on principal alone.

People like to bemoan the funding model, as well as the Mozilla Foundations broad overview and general "business vibe"

There's a few irritating ones on Android at least.

On desktop it's been solid since Quantum

Yeah same.

People on here love to go all doomposting on every little thing though, so for them stuff that they'll never actively interact with is automatically horrible. But them, I bet those very people are the ones that do "proper privacy stuff" like blindly turning on hardening settings, and then in turn also complain that Firefox "keeps making FF use more memory and be slower and not load pages properly" when they have changed so many settings that they'd in turn make a compelling case for why most companies don't allow so much fiddling with settings: It just leads to endless complaints.