Hi sevevo, glad to see yo on Mozilla Support Forum.

Try clearing Cookies and Site Data.

• Click the menu button. and select Options. Preferences.
• Select the Privacy & Security panel and go to the Cookies and Site Data section.
• Click the Clear Data… button. The Clear Data dialog will appear. ...
• Click Clear.

If it doesn't solved your problem, then feel free to ask in Reply Section.Thanks for raising your question in Mozilla Support Forum.

On top of that, my extensions (specifically uBlock Origin) stopped working all together, despite it being turned on.

Above solution seems to work for now, still doesn't fix my extension issue though.

Maybe your extension is creating main problem, so reconfigure your extension.

Try Opening your firefox in Safe mode. If it opens in safe mode properly then the root cause of your problem is extension. You can solve them by removing Extension.

• Find the Firefox icon or click Start and type Firefox.
• Hold down the Shift key on the keyboard and then click the Firefox icon.
• In the Firefox Safe Mode window, click the Start in Safe Mode option.

Thank You !