Firefox has "serious security issue" with every web page so now unable to open any page

After updating software and restarting my laptop (Lenovo running windows 10 or 11) Firefox now displays this message for every web page (this example from attempting to access Gmail, but same message with all other sites I have tried): "Be careful. Something doesn’t look right. Firefox spotted a potentially serious security issue with mail.google.com. Someone pretending to be the site could try to steal things like credit card info, passwords, or emails. mail.google.com has a security policy called HTTP Strict Transport Security (HSTS), which means that Firefox can only connect to it securely. You can’t add an exception to visit this site." I now can't access any pages using Firefox. Long term user, so I hope you can help me! C