Auto Smooth Issues on Godot

Godot Version

v4.3.stable.official [77dcf97d8]

Question

Hello, I have a question regarding auto smooth on Godot.
I am trying to use modular design for my game map, when it is a flat field there is no issue between each node. But when I tried to create a stairs there seems to be a shadow issue between each node (making it look like a line between node). If I change the fbx into Shade Flat (I’m using Blender to create my assets) the problem is gone, so I’m thinking that it might be auto smooth issues when node on different height. Is there any way I can fix this issue? Thank you.