I got locked out of my now 8+ year old account because I had set it up with an old ISP provided email which has since been deactivated. I can't migrate because I have to verify with the email and I can't change the email without setting up security questions, which also requires the email. Support can do nothing.
i used a Gmail account mostly for some videogames services but Google locked me out of that account after several years because i didn't provide a phone number for it after a few years and i refused to.... So a lot of my old game accounts can't be accessed anymore...
That's also why i'm considering wheather it is better to use an email provider or maybe use your own domain for that purpouse... Maybe the combination of both could be the best bet (by that i mean using an email provider like proton mail and using it with your own domain so you can control the domain if anything goes wrong).