blockbench model does not work correctly

I'm using this forum for the first time so I'm not really sure if I did it right.

I have found a problem that makes an additional layer from my model. Is it possible to remove it?

What am I doing wrong?

My minecraft version: 1.16.5

Mcreator version: 2022.1

Blockbench version: 3.9.3

I have tried different mcreator and blockbench versions but this thing appears only every time when I am trying to make a mod for 1.16.5. I can't choose another of minecraft because I have some reasons.