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Firefox issues with video playing and logins
(hexbear.net)
A place to discuss the news and latest developments on the open-source browser Firefox
So its likely not your ISP or other site issues. Looks like in another comment you said it could be an add-on. Like debugging skyrim disable all addons and enable then one at a time till you find the problem. If you do find the problem you might want to check the addons git and report a bug if not already found.
I tried that disabling addons helps with certain sites but not others. I can't find a clean fix.
Maybe try an uninstall and reinstall.
Before you uninstall in Settings -> Privacy & Security -> Cookies and Site Data, clear all site data and cookies.
That's all I got. Best of luck!
thank you sweetie