Web app doesn't work with Librewolf browser

Hi. I'm a user of the Firefox-based browser Librewolf. The web app has always worked well but one day, can't tell you exactly when, the web stopped working. It allows me to reach the login page, enter my credentials and continue, but it gets stuck in a blank page with a loading spinner and nothing else.

- The developer console shows nothing

- The network requests all OK (200)

- I tried by clearing all cookies and local storage, but it didn't work

I still can get my mail through Thunderbird, but I'd like to have it working on the browser too. Any idea to have it working again?

Thank you