Apps freeze when playing videos, reboot helps temporarily. Logs attached. I'm out of ideas, HELP

So I've been having a really annoying problem for the past 6 months or so.

Basically what happens, is that when I'm watching a video on the Youtube app, sometimes the app decides that it won't play any more videos until I reboot my phone. At first, the app will be buffering the video forever (spinning circle), then if I close the video and reopen / open another video, the whole app freezes when it tries to start a video, and nothing will help at this point except rebooting the phone. I can kill the YT app but it does the same if I reopen it.

Here is a video about what happens:


Here are logcat & last_kmsg (uploaded to zippyshare because files are 10MB big):
https://www65.zippyshare.com/v/2vRF3zYc/file.html

I think it started since I installed YT Vanced (about 6 months ago), but even after uninstalling it, I still have this problem.
This happens very randomly. Sometimes it won't happen for weeks, sometimes it happens multiple times a day. Only a complete reboot solves the problem (until it happens again). Lately, it happens every day in the evening, which made it very annoying.

Yesterday I tested if other apps also freeze trying to play videos when this "bug" occurs, and yes, multiple reddit apps also did it (as you can see on the video). I forgot to test it with other apps, but this reddit app produced the same symptoms: it completely freezes when trying to play a video.

The bug has never occured outside the Youtube app. So it hasn't happened yet that I watch reddit videos or any other app, and the bug starts.

As you can see on the video, as soon as the apps try to start a video playback, they lock up, freeze completely, and they don't respond.
The bug usually starts by me watching a YT video, and then the video suddenly starts to buffer (as if Wifi signal is weak or something), but it never continues. It just buffers forever. Then I close the video and open it again, and that's when the whole app just freezes.

To me, this seems like a case where an app or service takes exclusive control of the media playback API, and it won't let go of it, causing other apps to freeze trying to play videos because they can't take control of the API.
However, I went into Settings / Developer Options / Running Services, and killed every single service and background process on the lists, and this didn't solve the problem.

In the logcat, there is an error that Youtube throws:
11-16 09:48:52.514 23413 23413 E YouTube : Media progress reported outside media playback: PLAYBACK_PENDING

I couldn't find and other signs in the logcat, maybe someone sees something else. I am not really adept at reading android logs.

Is there maybe any way to find out which is the culprit app/service?

The device is an Oukitel K6000 Pro with Nougat 7.0 (stock latest version), rooted using Magisk 20.0 (when this problem started, phone was rooted using normal SuperSU TWRP method, it has since been completely reflashed and using Magisk for the past month or so).

Please help if you can, I would really appreciate it.

 

Vanced was installed via a Magisk module. I have since then uninstalled the module and wiped the data of the original YT and updated it through Play Store. Since I was using it through Magisk, the system partition was unmodified. Doing these should be enough, right?