Did it again, doing more testing.
The screen shots attached are from the 1.16.3 Vanilla running in the Minecraft Launcher. Nothing more or less.
I also have the same problem in eclipse using forge 1.16.3 where I am working on a forge mod that is the reason I went to Minecraft Launcher and tested 1.16.3 vanilla to see if I it was eclipse, forge, my code, or not.
Unless there is a way for my running code in eclipse in a separate setup/hard drive to interfere with the minecraft launcher which uses the appdata folder or visa versa.
Going to do some tests and document everything I can to narrow down what is going on just using Minecraft Launcher, I'll report back.
OK, cannot get it to do this today. Next time I will restart the computer and the game to see what happens. Funny thing is when it was happening I tried the same test with both 1.14.4 and 1.15.2 without any problems. And when I started 1.16.3 back up it happened again. Going to write it off as a weird glitch for now.
Thanks anyway, if it happens again I will try to get some screenshots to report back.
Yeah my computer is not that great, I know most people have the biggest and the best but I do not. It plays minecraft well enough but will not be making any videos at the same time. And my internet upload speed is crap, uploading a small video would take hours. Sorry, I gave the steps to reproduce. I can get a couple of screen shots if that helps.
So turns out I can make a video but it is not great, no way it will fit in the 10MB limit though, uploaded it to youtube.
https://youtu.be/Coi723Vq2PQ