Same exact thing happened to me but thankfully it was a throwaway account (on my domain in fact) since I knew there was risk - thankfully they didn't cancel the whole domain for it...

I've been using gmail for my domain (free gsuite legacy) for 10+ years though I'm careful to not do anything that could be misinterpreted on the service particularly through google photos or youtube

I actually used fastmail for 10 years prior to gmail but abandoned it in 2010 or so because imap/calendaring/etc. wouldn't meaningfully sync with my iphone but gmail had full free activesync (which I still miss a bit...)

I still keep a basic inexpensive legacy fastmail account just for some sieve scripts and cleaner smtp than gmail offers...