Ya so this is a classic red flag of something being wrong with your account. Assume it’s compromised. Disconnect any auto deposits you have to coinbase from your bank account and begin the process of migrating things to cold storage and using non custodial platforms like bitcoin well. Coinbase is a notorious honeypot for accounts getting compromised for one reason or the other. The email you got could also have been malicious somehow. Please be careful and at least self custody in cold storage your bitcoin. Coinbase is generally terrible and has horrible support too.