How do I stop player from pushing ground?

I’m creating a tiny solar system with a playable character, but the character pushes the planet he is on, and there’s alot of jittering if the planet is moving. Changing the mass of the planet doesn’t help, nor does making the planet kinematic. I have a build of a working version I made earlier, but I can’t recreate it. Why is this happening and how can I solve it?

Strange. Have you tried freezing its x, y, z positions in its RigidBody component?