Jupyterhub with Notebook7: no logout button

I’m running jupyterhub with the notebook interface for a course. After updating to notebook v7 and
setting c.Spawner.default_url = "/tree", the new notebook interface works fine except:
The Logout button is missing.

Any ideas? For the time being I am back to c.Spawner.default_url="/nbclassic"

Can you check if the metadata listed here:

get added to page config?

(page config gets passed to the browser in HTML source code)

No.

The only config dictionary I see looking at the HTML source in the browser is

  <script id="jupyter-config-data" type="application/json">
    {"allow_hidden_files": false,
     "appName": "Jupyter Notebook", 
     "appNamespace": "notebook",
     "appSettingsDir": "/opt/envj/share/jupyter/lab/settings", 
     "appUrl": "/lab", 
     "appVersion": "7.0.3",
     "baseUrl": "/user/meik/",
... many more entries...
}
  </script>

but there is no entry starting with hub... ore shareUrl.

Is your jupyter hub using jupyter-server 2.x or 1.x?

pip freeze says

jupyter_server==2.7.3
jupyterhub==4.0.2
notebook==7.0.3