Engine physics ticking is not consistent

Flax engine does not seem to have consistent physics ticks (possibly affecting other ticks too), its as if the engine tries to catch up lost time and never thinks it recovered.

Steps to reproduce:
1. Run game
2. Cause engine to hitch somehow (opening a popup window in editor in my case)
3. Observe faster tick rate

Demonstration video:

https://github.com/user-attachments/assets/ed654cdd-001e-45b5-9db4-128b62099156

The controllers here are processed in `FixedUpdate`, with their velocities multiplied using `Time.DeltaTime`.