Which step will fix this issue?
Add s3:DeleteObject permission to the IAM execution role of the AWS Lambda function in Account A.
Change the bucket policy of the S3 bucket in Account B to allow s3:DeleteObject permission for Account A.
Disable server-side encryption for objects written to the S3 bucket by the Lambda function.
Modify the Lambda function to call the S3:PutObjectAcl API operation to specify bucket owner, full control.
Explanations:
Grantings3:DeleteObjectpermission to the Lambda function’s role only allows it to delete objects, not IAM users in Account B.
Changing the bucket policy to allows3:DeleteObjectfor Account A enables Account A to delete objects, not IAM users in Account B.
Disabling server-side encryption does not impact object deletion permissions; encryption settings affect only data protection, not access control.
UsingS3:PutObjectAclto specify bucket owner full control grants Account B ownership of the objects, allowing its IAM users to delete these objects.
From my perspective, the answer is:
Modify the Lambda function to call the S3:PutObjectAcl API operation to specify bucket owner, full control.