>Once it looks like the request is coming from the correct region, they tell the Meta support AI that the account is hacked and ask it to send the verification codes to an arbitrary email address they control.

Dear Instagram, wtf. Why not send the reset to the account in question? Arbitrary email, wow.

Perhaps the attacker says that they email was also hacked and "this is my new email now". It sounds like this was a result of AI support and not a real person "And if you're part of the A/B tested accounts on which the AI support option is active, tough luck, you can't even turn it off."