U can check some remedies over here [https://support.mozilla.org/en-US/kb/firefox-cant-load-websites-other-browsers-can#:~:text=Click%20Clear%20Now.-,Check%20for%20malware,check%20your%20computer%20for%20malware.&text=If%20you%20still%20have%20problems,Firefox%20issues%20caused%20by%20malware. Support Mozilla]

Many site issues can be caused by corrupt cookies or cache&#46; '''Warning ! ! ''' This will log you out of sites you're logged in to&#46; You may also lose any settings for that website&#46; * [https://support&#46;mozilla&#46;org/en-US/kb/delete-cookies-remove-info-websites-stored Delete cookies to remove the information websites have stored on your computer] {web link} * [https://support&#46;mozilla&#46;org/en-US/kb/how-clear-firefox-cache How to clear the Firefox cache] {web link} If there is still a problem, '''[https://support&#46;mozilla&#46;org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode Start Firefox in Safe Mode]''' {web link} by holding down the '''<Shift> ''(Mac=Options)''''' key, and then starting Firefox&#46; A small dialog should appear&#46; Click '''Start In Safe Mode''' (not Refresh)&#46; Did this help? While you are in safe mode; Try disabling graphics hardware acceleration in Firefox&#46; Since this feature was added to Firefox it has gradually improved but there are still a few glitches&#46; ''[https://support&#46;mozilla&#46;org/en-US/kb/forum-response-disable-hardware-acceleration How to disable Hardware Acceleration]'' {web link}