OnlyOffice hides the fact that it’s Russian.

And is it fully compatible? Most Excel-alikes have at least some hiccups.

I would say no. With the recent debacle the writing is on the wall. Mozilla is not taking our privacy seriously. So, I have switched away from vanilla Firefox.

I would recommend using a fork instead: LibreWolf, or Floorp, or Zen; and Ironfox on Android. Mullvad Browser is another option.

Firefox has effectively become spyware, and so, yes, it ***should *** be replaced. There are several forks that work well. I’m using Floorp (stupid name, but really nice with some improvements over vanilla Firefox). Zen is another one gaining in popularity. Try them out! Don’t let Mozilla walk away with your data.