integration not working on my installation

Hello friends,
I'm facing a problem with this integration:
I've added my discourse installation address (live and working) to the "connected accounts" in the nextcloud settings, just after adding "web+nextclouddiscourse://auth-redirect" in the "allowed_user_api_auth_redirects" field on discourse options.
The connection somehow worked , even if I read "Connected as" without the relative username, see screenshot:

The integration seems not to be working here and the discourse widget on the dashboard shows an error. See screenshot:

I know this isn't a support forum, but there might be other people experimenting the same problem. Do you guys have an idea about how to solve the problem?
Does maybe the fact that on my installation discourse is managing authenticatications through discourse SSO on nextcloud (this works perfectly)?
I'm running Nextcloud version 21.0.3 , an updated version (yesterday) of discourse, and all the nextcloud plug-ins are updated.
Any suggestion? Being able to integrate discourse would be a must for the group I'm managing nextcloud for...
Thank you!

The report names Nextcloud 21.0.3, an updated Discourse installation, the allowed_user_api_auth_redirects setting, and a dashboard widget error; begin by reproducing the connection flow with those details and inspect the attached screenshots. Done means the account displays its username and the Discourse dashboard widget loads without an error; the issue does not name a source file or test.