The argument that "Google still controls Chromium so it's not good enough" is exactly the kind of FUD I'd expect to back up this kind of psyop, too.
I find this notion completely baffling. I use Chrome, Firefox and Safari more or less daily cause I test in all 3, and other than Safari feeling clunkier and in general less power-user friendly, I can barely tell the difference between the 3, especially between chrome and FF (well, other than uBlock working better in FF anyways).
I made some other changes, but I forget what. At least FF still has the full uBlock Origin.
Except the YouTube thing but that's because I'm not even sure what you're talking about: I leave YouTube windows open in Firefox for weeks.
It occurs to me that it could be a pathological edge case triggered by ublock and youtube interacting. I'm not going to disable it to find out.