I'm in the same boat too...

The same issue with the final public release of iOS 14. I've updated from iOS 13 to iOS 14 a few days ago and everything worked fine until today. For no reason, iPhone(Xs Max) rebooted and went into an infinite boot loop. When trying to restore it(in DFU mode), I get the following error: "The iPhone could not be restored. An unknown error occurred (4013)." Tried multiple times... Any suggestions?