As someone in a similar spot with a GMail account I've been using since they were invite-only, I've started using Google Takeout to back up an archive of all my data from Google's services a few times a year.

It's not perfect, and I'm thinking more and more about moving to a paid service, but this at least gives me some peace of mind that if one day I run afoul of Google's AI bouncers, I won't lose a decade of info overnight.