hello and welcome to the forum,
gdrive tokens expire after one hour.
when that happens, rclone requests a new token from gdrive.
now rclone has to save that token in the config file.
as i understand it, rclone
--- copies the rclone.conf to a temp config file with a random name.
--- writes that token to the temp config file.
--- renames the temp config file back to rclone.conf
so it could be a simple file/dir permissions issue.
which type of user is running rclone mount, root or non-root?
https://forum.rclone.org/t/fail-to-create-config-directory-on-synology-for-b2/18049
and this is the rclone source code
https://github.com/rclone/rclone/blob/555def2da7f425225b9f8657593733b5d71f901e/fs/config/configfile/configfile.go#L156