Faurazeko, have you tried the latest version 127.0.2?

According to the release notes: "Fixed an issue where YouTube playback may experience stalling under certain conditions"

Just updated. Didnt help

Just wondering, Did you restart Firefox / your PC after the update? Did you try troubleshoot mode?

i restarted just firefox, without pc reboot. Yes, i tried troubleshoot mode, problem persists while in the mode

Other things you could try are:

• Restarting your PC.
• Rebooting your router.
• Creating a brand new vanilla Firefox profile (without refreshing or manually importing any bookmarks or other data or otherwise making any changes to it) and seeing if it still happens.

If none of those work, and if no-one else has any other suggestions, then you could file a bug at Bugzilla: https://bugzilla.mozilla.org/home

Faurazeko, there is a bug report already, if you think it might be relevant to your situation: https://bugzilla.mozilla.org/show_bug.cgi?id=1900191

This was the bug that was fixed in the last release. If it applies to you you could post there to let them know that there still may be issues (if none of the other suggestions given in the previous post help).

i tried using firefox without a sync profile and with a new profile and it didnt help. Right now im using 127.0.2 and it seems like problem got even worse. Some videos doesnt even load now. I rebooted my pc and the router, trying with and without vpn but nothing changes. and it seems like guy on bugzilla have problems only with live videos while i have problems with all types of videos

Opened a ticket on bugzilla. Now it is closed. Seems like the problem is resolved in the newest firefox nightly