After a retart of Firefox version 99, I was unable to return to my profile, it seems as if Firefiox had scrapped my profile. I was unable to sign in to my profile, it did not recognized my profile, I thought I had lost all my config. I was unable to use Firefox for an entire day. Finally I succeeded in activating the synchronisation, but I had to reset all my extension. I regretted having upgraded to version 99. I am holding off updates on all other machines.