Great news: Support for Jottacloud OAuth (via CLI token) is “official” 
.
- The official production version of the OAuth handler web service has been updated (https://duplicati-oauth-handler.appspot.com/).
- Duplicati has been updated, released as new canary (v2.0.6.103-2.0.6.103_canary_2022-06-12).
Big thanks to @jthall for your valuable input, and for your effort with the beta oauth service! 
Please test with latest canary and report any issues. Not all of the steps described previously will now be necessary, but something like this:
- Visit https://jottacloud.com/web/secure and log in. Click “Generate” in the “Personal login token” section, and enter your password again. Copy the resultant CLI token.
- Open Duplicati, and edit a backup or create a new backup.
- Click the “AuthID” link to open a “pop-up” with the official OAuth service showing Jottacloud only. Alternatively just open the main page of the oauth service at https://duplicati-oauth-handler.appspot.com in another tab. Click “Jottacloud login”, paste in the token obtained in the previous step and click “Login”. Copy the resultant AuthID.
- Paste in the AuthID you obtained previously in the “AuthID” field
- Click test connection and if successful, click through with next and then click save.
Note that if you want to continue to use the same configuration as you have tested the early beta with, you need to remove the “oauth-url” option from the “Advanced options” to make it use the default production oauth handler web service, instead of the beta service that was set up for previous testing of this change. Also remember that you need to generate a completely new CLI token and AuthID, as described above, and replace the existing value in the “AuthId” option.