I'll try to go easy, but per previous posts:
- Your YouTube addon is not the latest 'Alpha' version
- Your Kodi version is out of date
- Your LibreElec version is out of date
- Not sure about the CoreElec version (I thought it wasn't even properly developed/supported anymore?)
- Because of the above I guess InputStream Adaptive will not be the latest version either
You also don't state if you have MPEG-DASH Enabled or Disabled or what Video Resolution you have chosen.
Yes, Google is making life difficult for us at the moment. But having totally a totally out of date and/or poorly configured Kodi setup may not be helpful either...
Please don't take my post personally @
sprocketoctopus - it's really meant as an example that it is very difficult to compare like with like with so many variations in individual setups, especially out of date setups.
I previously posted my totally up to date system as an example of what is working well for me, and in order that other users can also maybe try that if they are having issues.
Hope it helps