I watched your video recording. I have no expectation of:
Because, I am accustomed to failures of multi-tasking ← failures caused by hardware, software, and network communications . . . PLUS the burdens placed upon all of that, by the user.
For sure it’s a bug in Brave as already 2 more people on this topic confirmed the same issue.
Nope. Honestly don’t think I’ve been seeing this complaint elsewhere.
Was trying to think why I didn’t reply or try to help you on this but think I’m seeing why now. Looking at your original post and some others, you provided no details really. When people create topics, it generates a template which at least asks for some basic information. Seems you deleted it but then never said anything about which specific OS, which version of Brave you’re using, what specific steps are needed to try to replicate the problem, etc.
That said, since you tagged and seem to be trying to figure it out, I’ll ask you for a bunch of information that would be helpful to know as well as some things for you to test.
What version of Brave are you on? (provide exact number, such as 1.23.456)
Which OS are you on? I see the windows tag but which one? Windows 10, 11, or what?
Does it ever happen in private window?
If you disable or remove your extensions, do you notice the issue still happen?
Have you tried changing the toggle for Use graphics acceleration when possible at brave://settings/system to see if anything changes? (When on, it tries splitting tasks with your GPU for better performance. When off, it fully uses your CPU. Usually want GPU but depending on card and settings, toggle makes a difference)
Do you have Memory Saver enabled at brave://settings/system? If so, does disabling it have any impact?
If you create a second browser profile, do you have the same issue there? Click on the hamburger menu 
→ More Tools → Add new profile and create one. This will have a secondary browser profile with no extensions and most of your settings at default.
If you install Brave Beta or Brave Nightly, do you see the same issue there?
Can you check to see if it also happens on Chrome?
Doesn’t mean it’s a Brave issue. It could be that all of you use the same web extensions, have toggled a setting, have some VPN or firewall interfering, or a million other commonalities.
This also kind of confirms what I was saying. If it’s happening in other browsers then could be a Chromium issue, which often has to be fixed upstream by Chromium. It’s part of why I asked if you could see if the issue happens in Chrome as well.
Also want to point out that the people on the Vivaldi issue you had are saying that in their testing it only was happening on certain websites or content.
Another thing to note is:
What that would say is that it’s a change that happened in Chromium in updates after 132. Opera didn’t have the issue because it was on Chromium 132. Firefox wouldn’t have had the issue because it uses Gecko instead of Blink (Chromium).
So if it’s the case as they told you, then it’s an upstream fix needing to be done. The Chromium team would need to fix it, as it’s something that may be impacting all browsers.
But then also is interesting as it seems they are saying isn’t happening on all sites or anything. It seems to be very niche. The bigger headache is they say it seems to only be happening on certain sites and bad players. But if you have on Youtube or other sites, it may be important for you to submit the issue to Chromium team.
I’ll tag in @Mattches on this just so we can know someone from Brave is aware. And I guess they could review your info at https://forum.vivaldi.net/topic/107532/audio-desynchronizes-from-videos-if-i-move-to-other-tabs as well, but based on what I’m seeing I don’t know that theres much that can be done.
Hello, thanks for response. You were right, I don’t remember why I deleted it at first, can’t remember, but next time when I’ll make a topic I will not delete it. Sorry, my bad.
1.77.97, the latest.
Unfortunately, it does. And I didn’t use any kind of addons, too.
Here’s a recording in private window which showcases the issue:
I didn’t use any addons.
By default I tried with the setting on. Here’s a recording when I turn the setting off, and the issue sadly, still persists.
No, it’s not enabled.
It still persists. In fact, in the recordings, the Brave installation is clean, without addons or other stuff imported.
Yes, still there. Here’s a recording:
Tried right now, sadly, it does.
A little update:
I downloaded Opera developer right now (today version 120 got released) and the issue is there.
So you might be right. It might be a Chromium issue, and it’s quite likely happening at 133 or 134+, as currently Opera developer is on Chromium 134.0.6998.35.
A little bit off-topic, but I also reported this issue on the Chromium bugtracker.
Update: It’s a Chromium issue.
Starting with Chromium 136 it was fixed, so we’ll have to wait until then.
@Mattches sorry for tagging, but I have a question: can the fix from that link be somehow imported a bit faster into Brave or we really need to wait until Chromium 136?
If the issue is upstream (as that one is) then unfortunately our hands are tied for the most part.
