You could also start a new Firefox instance via command line (or desktop-starter or whatever) using firefox -P --no-remote and can start another instance with another profile and also run multiple profiles in parallel.
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I tried switching to Firefox and found that it's multi-user feature is crap.
I just need two clicks to switch to another-user in Chrome.
But in Firefox, I need to type "about: profiles" in address bar, press enter, scroll down, and press the button to switch to another profile.
In the end I decided to switched back to Chrome and wait for Mozilla to optimize the UX of switching profile in Firefox.
I don't want to use multi-user. But it's a good reason
You could also start a new Firefox instance via command line (or desktop-starter or whatever) using
firefox -P --no-remoteand can start another instance with another profile and also run multiple profiles in parallel.