If you are using a private VPC, private subnet, and ECS, ensure you create the following 4 VPC endpoints to enable ECS tasks to pull images from a private ECR repository:
S3 Gateway Endpoint: Required because ECR images are stored in S3. ECR API Endpoint: For ECS to authenticate and interact with ECR. ECR DKR Endpoint: To pull container images from ECR. Logs Endpoint: To send ECS logs to CloudWatch (if configured). Once these endpoints are set up correctly, your ECS task should be able to pull images from a private ECR repository.