Sorry to tell you, but this is just the default answer of these stupid "Microsoft employees" / volunteers that should actually have been replaced by more capable bots long ago I doubt it ever even helped a single person, would be highly surprised if...
Also the same for me! First happened on December 30; the Dec 23 backup was still fine. I'm on Firefox Beta channel so if anything changed on that end, I should've gotten it pretty early. Interestingly, the failed backups can still be selected for res...