The problem with using 'gsutil cp' is that only the gstmp file is generated.

The following instructions were executed in order, and it was confirmed that the subdirectories could be confirmed normally.
(I couldn't see it at Mount.)
1) gsutil -m ls -al "{BUCKET}"
2) gsutil -m cp -r
3) ls -al

However, when I checked it in GCS Console, it was overwritten with the gstmp file.

The gstmp file is a temporary file that is generated when you download or upload a file from gsutil, and because the file is not properly uploaded / downloaded, it cannot return success and is known as a remaining file.

Please tell me the cause and solution.

Start by reproducing the listed gsutil -m ls -al and gsutil -m cp -r commands, then compare the local results with the GCS Console and the remaining gstmp file. Done means identifying the cause of the incomplete transfer and documenting a verified solution.

Written by the indexing model from the issue text.