Did you read here?
https://www.reddit.com/r/CoinBase/Many users have the same problem as me. However, unlike them, I have not received any email about closing the account. We have in common that we cannot withdraw in any way.
I checked that, some users got varying penalty levels.
If I were to interpret the reason for the suspension as "violating coinbase standards" which has yet to be stated, I think the opinion of some of
the user comments there is correct that Coinbase appears to be doing a massive user screening and promptly taking appropriate action if it is potentially disadvantageous to their position to face SEC lawsuits.