EDIT: Apologies. Updated with a link to what gorhill REALLY said:
Manifest v2 uBO will not be automatically replaced by Manifest v3 uBOL[ight]. uBOL is too different from uBO for it to silently replace uBO – you will have to explicitly make a choice as to which extension should replace uBO according to your own prerogatives.
Ultimately whether uBOL is an acceptable alternative to uBO is up to you, it’s not a choice that will be made for you.
Will development of uBO continue? Yes, there are other browsers which are not deprecating Manifest v2, e.g. Firefox.
Meh.
Librewolf already breaks loads of websites with it’s fingerprinting resistance - just get used to turning it off.
In any case, you already need a chromium fork handy for all the sites that just plain don’t support firefox any more. I’ve run in to weird issues in firefox that don’t arise in chromium several times in the last month. This is going to get much worse.
As for changing browsers. I don’t care very much. I don’t use many browser features like bookmarks or passwords.
Which websites did you run into issues with Firefox? I haven’t had any issues with any websites. I do think you’re right that it’s probably going to get worse over time, but maybe not if more people make the switch to Firefox.
booking.com is the worst I’ve encountered. There’s a captcha type anti-bot thing that I can’t pass with firefox. I think it uses canvas.
edit: another I use all the time is called echo360. It’s the platform my university uses to host lecture videos. The player just plain doesn’t work in firefox - blank screen.