Problem with filenames, perhaps encoding

Today I had a problem opening a notebook, named: probabilità_singola.ipynb. I received a 404 error.
I renamed it to ps.ipynb and it worked fine. so I guess it’s some weird problem with encoding. is this behaviour expected?
My jupyter hub 1.3.0 runs on linux debian bullseye, python 3.9 and en_US.utf8 locale.