The right response isn’t panicking about a hacked account, it’s treating unexpected chess.com emails with more suspicion than usual and checking whether that same email address has turned up anywhere else, since reused credentials remain the far more dangerous exposure than anything sitting in this particular file.
The correct response is use lichess.org
But chess.com has advertising and subscriptions!
Pshh, this website is full of children. When your ready for a thinking man’s game Checkers.com will welcome you.