Earlier quoted context omitted.
Firefox has always had profiles, very much acting like Chrome's, but for some reason they didn't make it easy to use. Navigate to: about:profiles Now you can have multiple windows, each window with its own profile and the profile determines everything, from the browser's history to the extensions installed.
I have tried them but it wasn't simple to use multiple profiles at once, nor was it obvious which profile you were using. I felt as though Firefox was discouraging their use. Are you using them? Here is an article that talks through the steps (on windows but it's similar for others) https://www.howtogeek.com/209320/how-to-set-up-and-use-multi...
Before the Quantum release we had a pretty cool extension for managing profiles that is no longer available, sadly:
https://web.archive.org/web/20181102210053/https://addons.mo...
I hope it gets implemented again.
I now do the "about:profiles" thing I mentioned. I don't know why they aren't exposing Profiles in the UI in an intuitive manner, makes no sense. For my day to day use, I think Multi-Account Containers are better though.