I got the same problem on a couple of Google accounts.
The only pitfall advice from Google was to try to log in from an old machine or a previous location. This has never worked, and accounts are lost as there is no way to be in contact with a human to assist.
This time is different. It's got something to do with G$$GLE's policy to charge the Gmail users who happen to use their E-Mails under the so-called "G$$GLE Workspace". I know this for sure because I use Gmail under "G$$GLE Workspace" and today I'm greeted with a message like this "Your 14 day trial period for G$$GLE Workspace has ended. If you want to use G$$GLE Workspace , start a (paid ;) subscription." All of this happened after I've been using it for more than 12 years!
The only pitfall advice from Google was to try to log in from an old machine or a previous location. This has never worked, and accounts are lost as there is no way to be in contact with a human to assist.