Glitchy 3D Rigidbodies

Godot Version

4.2.1

Question

Hi, a beginner here.
I tried to use the Rigidbody3D for the first time and it seems to be really glitchy. It does fall in a logical way and kind of behaves in a logical way but the problem is when I walk over it(with this FPS script : Quality First Person Controller v2 - Godot Asset Library) it just starts glitching out. also jumping near it seems to sometimes launch me into the sky. is there any way to fix that ?

Give it some mass, or increase inertia.