@mahendrapaipuri you’re right, it works on Firefox, my mistake! Thank you so much for taking the time replicating my env.
It looks like the origin of the problem is chromium browsers core. I wonder if there’s something I can do to make it work for chromium based browsers (Chrome, Brave, Vivaldi, etc.). Any “dive-in” direction would be highly appreciated.
I’m using TLJH installation.
BTW, I simplified the setup with only one file now:
/opt/tljh/config/jupyterhub_config.d/jupyterhub_config.py:
c.JupyterHub.tornado_settings = {'headers': {'Content-Security-Policy': "frame-ancestors *;"}}
c.Spawner.args = ['--NotebookApp.tornado_settings={"headers":{"Content-Security-Policy": "frame-ancestors *;"}}']