Komunitné fórum Firefox

When I click on a website the page is completely blank. Not loading, no error message, just white. It happens on a lot of web pages but not all of them. Youtube is fine but a lot of others dont. there doesnt seem to be any pattern to the type of websites that dont work. sometimes the website will work the first time but if I close the tab and then click on the link again it wont work. It seems like the code of the website has somehow been deleted? (see photos). Ive tried disabling literally every extension I have and reloading the page but nothing happens.

for about a month my firefox home screen is greyed out in the "thought provoking stories" and it is continuously flashing. Everything works, ie. I can still search the net, etc. but this is driving me crazy. I have tried everything from checking settings, through extension conflicts and resetting, but nothing makes any difference. I even uninstalled and reinstalled Firefox but it came back with the same problem. i have windows 10 and am getting ready to upgrade to 11, but I would like everything working as it should before doing the upgrade. I even tried to change my profile, but I'm not sure how to do it and it made no difference. Any help will be much appreciated.