Your fear is rational. It's happened to other people. I would suggest going to a paid provider like Fastmail and checking their terms of service. I don't know of any protections that exist by law at the moment.

My horror story:

I have a mentally ill relative who only logged in every 6 months. He got treatment and wanted to resume using his email account. Guess what? Google thought his activity was "suspicious" and permanently locked him out. We went through an infuriating loop of proving his identity, then getting a message saying a human was reviewing it. Then we'd go back to proving his identity. This went on for 15-20 cycles over the course of 8 months.

The only way to get out of it was to contact my friend who works for Google. Otherwise my relative had lost gigabytes of irreplaceable data. We would've gladly paid $1,000+ for the privilege of talking to a real human about it, but that's impossible.