Why do plane objects have glitches shadows?

Godot Version: Godot 4.2.1

I created models in BlockBench, then exported them into Blender where I could Edit them in a bit more detail and such, but as I exported it into GLB file, then I opened it in a Godot, it all looked normal until I put in lights, when I turn on Shadows, it makes all plane objects flickery or I don’t know how to describe it, I assume it’s because of polygons, but I didn’t seen anybody talking about this issue, so I decided to write here if anybody knows how to fix this issue, below is a link to google drive with all the images. I don’t know where to ask for help about this then here, sorry if I’m not supposed to upload or ask for help here and such, I never posted on forums ^^’

https://drive.google.com/drive/folders/1Ugmz4dTgC6Id4n8p3lB1F20U2OmMNuEy?usp=sharing