Firefox

Never seen this. Do you have some kind of browser extension or malware?

Nope, never happened to me in 10+ years of usage, except when completely reinstalling after wiping everything.

Do you still have the Google search engine added? I always fully remove it, since Searx pulls from Google anyways, I don't really see the point in keeping it.

Not at all.

If an update causes me any problem, I can reboot to a snapshot (3 hourly, 3 daily, 1 weekly) and if it's an issue with my Firefox profile folder, I would just copy back one of the rsync backups:

I have the benefit of experience, I loved my Nokia 3210, bought a Nokia 3310 - but managed to lose it a few years later... and was shocked because I had no record of contacts/phone numbers.

With Firefox, I learned that trying out a new version could 'update' the profile, and then reinstalling the old one wouldn't work with that profile (I had to use sync to restore it). Since then, I always have a snapshot of the entire system, plus regular backups to defend against hardware failure.

Some people believe in Evolution, they think that the world would move forwards...

These days it's so trivial that it's hard to estimate the intelligence of anyone who doesn't do it, and then complains that something went wrong.

Never had this problem. I'm using Firefox on Windows and Android with another search engine for years now.