Youtube videos not playing on safari and Firefox.

I am using this computer for about 3 months now, I bought old laptop from 2016 (I guess), its running MacOSX Big Sur 11.6.8.

For about a week now, I am trying to play YouTube videos but its not loading videos only a waiting circle is rotating. same thing is happening on Firefox, so I guess there is some problem in OSX or safari. page browsing and everything is normal, just video is not loading, I can see thumbnail on timeline of video but video is not running. I cleared cache and did every step I could find on internet but nothing is helping me.

Please guide.