URL: https://www.santander.com.mx/MiSitioPrivado/

Browser / Version: Firefox 88.0
Operating System: Linux
Tested Another Browser: Yes Chrome

Problem type: Site is not usable
Description: Page not loading correctly
Steps to Reproduce:
Website freezes on the loading screen, works con Chrome and Chromium based browsers, doesn't work on Firefox 88 on Windows, it doesn't work on Firefox ESR 76 on GNU/Linux
It used to work around July 2020

View the screenshot

From webcompat.com with ❤️