Top cloud security risks: misconfiguration (#1), insecure interfaces/APIs, account compromise, insufficient logging, insecure data storage. AWS is responsible for security OF the cloud; customers for security IN the cloud.
ENISA, CSA, and Gartner consistently rank misconfiguration as the #1 cloud risk. Enable cloud-native security services (GuardDuty, Security Hub, Microsoft Defender for Cloud) immediately on new accounts.