Make sure you are not blocking content.

https://support.mozilla.org/en-US/kb/enhanced-tracking-protection-firefox-desktop also see https://blog.mozilla.org/security/2021/03/23/introducing-smartblock/

https://support.mozilla.org/en-US/kb/smartblock-enhanced-tracking-protection

Diagnose Firefox issues using Troubleshoot(Safe) Mode {web link}

A small dialog should appear. Click Start In Troubleshoot(Safe) Mode (not Refresh). Is the problem still there?

Many site issues can be caused by corrupt cookies or cache.

Warning ! ! This will log you out of sites you're logged in to. You may also lose any settings for that website.

• Delete cookies to remove the information websites have stored on your computer {web link}

• How to clear the Firefox cache {web link}

Disabled smartblock and tracking protection still disconnect me from youtube livestream.

And the rest of my post?

Great ive finally know what causes problem.

When used Troubleshoot Mode and all addons are disabled chat on youtube livestream function normal. Closed Firefox and reopen, all addons are active and youtube stream still got disconnect messseges. So ive start disable addons one by one to check what cause problem

And there you go this addon are faulty, little strange he never caused problems before, and i used him because youtube removed that function two years ago https://addons.mozilla.org/en-US/firefox/addon/gotochannel/

That was very good work. Well Done. Please flag your last post as Solved Problem as this can help others with similar problems. Go to that post and click the 'Solved' button to its right.

You should also contact support for that add-on so they can fix it.