It is definitly not API calls.
I agree with this:
It is the way Plex downloads the file multiple times to build the library. This exceeds the download quota if files are not cached.
I had a script running, moving lots of files with rclone in the same time of plex scaning the plexdrive mounted folder. It may be that which trigged the ban.
That happen with rclone.
That does not happen with node-gdrive-fuse
That does not happen with google-drive-ocamlfuse
That should not happen with plexdrive.
As I have several gogle drive accounts, I can scan and rescan to test, without be disturbed by the ban, for testing purpose.