Youtube grayed out after login
Everytime I use an expecific google acc, the youtube don't load properly, it stay on a page with only gray fields (ss in attachment). Google Chrome and Edge ok with the same account.
If I try another acc, it works; Deleted history, cookies and extensions don't work; Safe mod don't work; Reset Firefox don't work; With or Without sync activated, don't work; Tried on versions 76.0.1, 76 and 75, same problem; After a fresh install, the first login and visit works, but if i close the tab and try to open again, the problem appear.
I found the same issue years ago here (https://support.mozilla.org/en-US/questions/1236715) but the workarounds there don't helped me.
Thanks for the attention and i'll be glad if someone can help me. After many time in firefox i don't want to migrate to another browser bacause only one website.