Will the EU enforce the same for 3rd party integrations?
If Apple extended that philosophy to other vendors then yeah, it would be deliberately unfair and anticompetitive.
Even if you could make all the other possible vendors run private cloud compute style stuff that would be a lot to manage.
And I can’t imagine the EU would like, and as a user I would certainly hate, the “OK you can use Grok but you lose all privacy too bad“ dialogue box they could make.
Most sysadmins know that hash matching only mitigates a small subset of rare upstream attacks. Apple could still be MITMing the whole thing (SSL added and removed here :)) and no auditor would get the chance to check. The offered audit is so weak that I would not trust any FAANG business to administrate it.
Apple is once again demanding arbitrary centralization to give them an undeserved veto power. None of this is for security.