Oh man, I hadn't even considered foreign relations.
Consider that Biden just fucked over France with that Submarine deal, and by fucking over France, pissed off the EU, because only the EU is allowed to act as a trade union, everyone else is just supposed to bow down to them. Consider how many countries he fucked over with the botched Afghanistan pullout. Consider AOC's little stunt with trying to withhold the Israeli Danegeld -- didn't Biden refuse to sign some pledge to support Israel even if (when) they commit war crimes, too?
If AZ is de-certified and the wind starts blowing that way... Which foreign nation will be the first to declare Biden illegitimate and officially cut off contact? Who will cast that first stone? Or will they just claim that some policy change or deal that Biden tries to make isn't official US policy because he's not the leader of the US.
Russia? China? Some smaller nation?