Depends on D20113. Ref T6703. Continue moving toward a future where multiple copies of a given type of provider may exist.
Switch MFA from session-MFA at the start to one-shot MFA at the actual link action.
Add one-shot MFA to the unlink action. This theoretically prevents an attacker from unlinking an account while you're getting coffee, registering alIce which they control, adding a copy of your profile picture, and then trying to trick you into writing a private note with your personal secrets or something.