waterfox

[http://dummy.us.eu.org/robert (Robert)]

I installed the newer waterfox alongside your existing waterfox classic.

You can try it, but it's possible that it will be a one-way thing, i.e.,
some extensions such as look-and-feel may permanently change and there
will be no turning back.  Up to you.

https://www.reddit.com/r/waterfox/comments/ett2nj/difference_between_waterfox_current_and_waterfox/