Happened to me too after 10 years of Gmail use. Exactly the same story. No explanation. As I remember at that time I checked Google servers data as to uptime—the data was public, not sure about now—and it appeared that there was a serious problem with servers right before I was blocked. It looked like Google just completely lost data in some server cluster. Anyway, there was no way to get any response from Google or at least my gmail address reactivated even with data lost for me to be able to access other services that I used the email to access. I think it was Google's fault. The company lost data, but didn't want to admit it and blamed me for breaking some policy without any further details to explain absence of access to my data.
Since then I use my own domain for email, could easily switch email provider while keeping the address in case there is a problem, and I'd still control access via the email to other services. Also I never rely on Google as to files, photos, or videos. I mean yeah I use Google, YouTube etc., but everything is first of all backed up on MS OneDrive. Even on my Android phone there is automatic upload of all new photos to OneDrive. Google Photos is more like for easy viewing, sharing and presentation. Not backup. Not to mention that MS Office + OneDrive storage subscription provides much more value that Google G Suite.