Jottacloud removed basic authentication, Duplicati can no longer connect #4697 talks about this token:
Note: rclone supports using Jottacloud’s “personal login token”, which is used by their command line app. Code here: rclone/backend/jottacloud at master · rclone/rclone · GitHub
I am assuming that CLI token and personal login token are the same thing. The latter is in rclone docs.
The Go language code cited by the issue has a URL with openid-connect in it, so supports the theory
which Duplicati can’t do AFAIK, though it does do OAuth (which underlies it) in Duplicati OAuth Handler.
If someone wishes to look into such areas more, it could be useful. OAuth changes do arise sometimes.
Duplicati - Dropbox Backup - Short lived token expires is the recent breakage from server-side changes.