Thanks for adding these details.
Do you have any special browser plugins/extensions?
Have you tried it in a different browser?
I think we can at least test if it is your local system or browser. Does it happen if you open a session on a remote computer clicking here and try in a new notebook there?
That uses Jupyter Notebook 7.1.3, which isn’t the version you reported, however, is the version reported by the post that seems to be raising the same issue here.