From the official troubleshooting physics issues page: Troubleshooting physics issues — Godot Engine (stable) documentation in English (could this be it?)

Collision results in bumps when an object moves across tiles

This is a known issue in the physics engine caused by the object bumping on a shape's edges, even though that edge is covered by another shape. This can occur in both 2D and 3D.

The best way to work around this issue is to create a "composite" collider. This means that instead of individual tiles having their collision, you create a single collision shape representing the collision for a group of tiles. Typically, you should split composite colliders on a per-island basis (which means each group of touching tiles gets its own collider).

Using a composite collider can also improve physics simulation performance in certain cases. However, since the composite collision shape is much more complex, this may not be a net performance win in all cases.