You can revoke the certificate, if you want. Issuing a new one won’t invalidate the old one - they will both be valid simultaneously.
That said, if you believe the server was compromised, then it’s more than just your certificate private key which is compromised, it’s also your Let’s Encrypt account, which is at least as bad.
Better to start over with a fresh
/etc/letsencrypt, or at least,
certbot unregister and
certbot revoke to invalidate your old account and then revoke your certificate from your new account.