There is a bug I am getting, to fix that I am editing config files and even disabling 3D layer for head is doing nothing for me.

The file won't auto-reload. You can access the config in-game on forge if you have https://www.curseforge.com/minecraft/mc-mods/gamemenumodoption.

It even not working after rebooting the game. This is the issue.
Also I have almost same mod for configurating mods directly from the game called Configurated, and even it can't detect working config for this version. I am on 1.16.5 and latest forge version. With all mods updated.

Then try to use the config menu accessible via the main menu mod list. I don't know Configurated, so can't tell you why it might not detect a normal config screen.

Any update?

I was trying to initiate an issue again across the whole december, and it is randomly disappeared. I think that issue is closed. Thanks for help.