Can't log in to websites

I noticed this problem when I couldn't login on facebook and initially thought it was a website problem. But I tried logging in to other websites where I have accounts (gmail, yahoo etc) and I either get error messages like "session expired" or it keeps bringing me back to the login page. I have this problem only on firefox mobile, I tried multiple logins from desktop and I have no issue. I've looked for help online but nothing has worked. Solutions I've already tried: clearing all cookies and cache (even from my phone settings), checking that cookies are enabled - they already were and I even tried disabling and enabling again. Still can't login. I'm using a Huawei Mate 10.