Firefox has been my main browser for a long time, and I barely even noticed the UI refresh with 94.0. It is set to use whatever the UI defaults are; I've never changed them. My only customization is to use the extension for multi-account containers. Firefox looks nice to me, does what I want and expect, and it feels fast. I suspect that for many (if not most) people who simply want to get their work done, like me, slight tweaks to the UI are not and have never been much of an issue.