Buggy floor levels when walking without guardian boundary

Hello, I am developing a VR application that requires the user to be physically walking while wearing the Quest Pro headset. Since the physical environment the user will be walking in is inconsistent and the distance walked will be long, we have disabled the guardian boundary. However, this seems to have resulted in the floor level constantly regardless of the physical location.

May I ask for some help? How can I get the floor level to remain stationary while walking long distances without the guardian boundary?