How do people manage selling or changing a domain they've been using long-term as their primary email address for sign-ins like this? To stop a new owner of that domain from taking over accounts sign-ins that use that email address, you'd need to reliably update all your sign-in details with anything you've signed up to?

You could use a password manager to track everything you've signed into before to help with this but that's error-prone.

Alternatively, this forces you to keep paying for the old domain indefinitely?