I'd never heard of Waterfox before. I downloaded and installed it yesterday to see what it's like and it works just fine. It imported all my bookmarks and extensions from my Firefox browser during setup. Worked perfectly. I had to go into extensions and manually enable the ones I still wanted to use.

It's certainly faster loading and running than my pre-Quantum ESR Firefox browser which I never really use anymore since I adopted Vivaldi browser a number of months ago.