Unity AR: Objects and physics are relative to the phone coordinate system but should be relative to the real world

All the objects, planes, and also physics in my Unity AR Core project are relative to the MainCamera. If I move the camera, the objects stay at the same relative position to the camera but should instead be fixed in the real world. I need a hint, of where to look for the error in my setup.

I set up a new AR Core session in Unity and want to throw objects into the world. These should fall on the ground plane (planes detected by the AR Plane Manager). The objects I throw, fall in a trajectory on the phone screen but are not affected by phone movement. -> not as an AR App should work.

I can also provide more information about the settings if needed.

I opened a new project and copied all the relevant game objects in the new project. It is working now, so I think there was a component missing in my previous project, which caused the unwanted behavior. I use the new project now to continue. -> no further input needed.