aws s3 moving file is copying again instead of just renaming the path

Question

I have a file in s3 bucket

S3://mainbucket/fold1/fold2/file.txt

Now i want to move to the below path

S3://mainbucket/fold1/file.txt

I am doing

aws s3 mv S3://mainbucket/fold1/fold2/file.txt S3://mainbucket/fold1/file.txt

I see its copying the file instead of just moving.

I mean it will take time again.

Why its happening so.

Moving should be just changing the path.