treyb So far, nothing. I'll check tomorrow if it no longer works.
The access token is never provided - you just put your refresh token into the extension settings. I believe the package I use obtains an access token every time under the hood.
I've released v1.1.0 that allows the use of the same adapter (eg. gdrive) multiple times (for hopefully further customizability in the future).
It also contains a test button for Google Drive where an access token is retrieved in the frontend to check whether the client details and refresh token work.
In addition, you may want to check the credentials being used at the moment of the backup by running the backup command with -vvv to display the most verbose output for debugging, if you weren't already.
