Thank you so much minrk!
Updating the environment variable via c.DockerSpawner.environment.update({"JUPYTERHUB_ALLOW_TOKEN_IN_URL": "1"}) did the trick for me.
It’s crazy that literal days of googling, searching forums and discussing with LLMs did not lead me to Tokens in URLs, Changelog or URL Token parameter now disabled?. Either I messed up big time regarding my search terms or search engine degradation is very real.
Since the token option has been disabled for security reasons:
Are there recommended best practices that I should use instead?
I am not strictly required to authenticate users via token. I just don’t want to force users to interact with two different interfaces to manage servers or log in multiple times.