Some say that fw v379 and last Youtube update from Aptoide.TV resolved the 4K 60fps stuttering issue.
379 is best so far. If for some reason you dont like it, you can flash older firmware same as you flashed 379.
In addition to Android reset open "TV Settings" from remote, selevt "Video" and scroll down to Video reset. This way all processing mode switches will reset.
Also very usefull after version upgrade to perform operation in factory menu: enable hotkey, perform NVM reset. But it is accessible only from remotes with numpad.
Don't even bother to update tour TV anymore. At least until Android 10, if we ever get it. Whatever change TCL did in V300+ firmwares, they are not going back. Those who face this issue should stick to V2xx and just be happy with it. Upgrading / reinstalling apps / downgrading, takes a lot of your life time, lol.
And this subject is like a war in forums. Not every TV has this issue, so, those who don't have it, think we are like idiots.
I'm running V270, the latest pre-3xx to my region, on my 50P8M. YT 4K60 is buttery smooth and HDR is also fine in PC mode
If you are annoyed about the stuttering, you should definitely give an older firmware a try. I recommend you to find the latest 2xx for you region. I know the latest of all is V295. A very common is V288. The latest to my region is V270.
I immediately noticed the stuttering when I first update my TV, if I'm not wrong, to V308 months ago. I first thought I broke it somehow, because the playback performance was a lot better before. Then I luckily leaned about the downgrade procedure and that solved everything.
The old interface is basically the same. You're still running Android 9. The only difference (aesthetic) is the TV settings menu (not the Android Settings menu, but the one you access using the remote button).
If you use an OTA package, the procedure is the same as to update the firmware. Copy the .zip to the USB drive, plug into the TV, go to Settings -> About -> Software update -> Local update and confirm that you indeed want to use an older version of the firmware.
If you use a full package (IMG), then you have to copy the .img file to the USB drive, plug into the TV, turn it off (full off, by long pressing the power button) and turn it back on by holding the TV's power button. Hold it until the bottom light starts to blink.
In both cases a full reset is recommended. The IMG will reset personal data, but will not reset NVM.
Ok, i try the v252, the last for my region, and the playback is perfect. Thanks for help! The system is not fluid like the 3xx version, but nevermind, the playback is the important things. I heard that the v252 causes crash in recovery mode, i'll try it, if the problem exist, i'll update to 288. Now perhaps is perfect, thanks!
P.S. The only "problem" (if we can call problem) is youtube, the last versione crashes on playback, but with the standard version is okay, so nevermind. Maybe the v252 is too old for this version of youtube, but amazon prime works good!
Yeah, the latest YouTube is indeed crashing when it starts the playback. It started to happen after the latest update from Play Store. I believe it will be fixed.
You have the option to use Smart YouTube TV. It's an alternative version with much more control. It's the same UI. I'm using it since forever.
I suggest you to use V650 IMG file, as your version is very old.