I have set Post-exposure to -5, but the build is much brighter than in the editor.
What unity version?
What headset?
Linear or gamma?
Unity version = 2021.2.10f1
Headset = Oculus Quest 2
Color space: Linear
Could you try and reproduce in a blank project?
If it still happens there, make a bug report
Were you thinking Linear or Gamma might be the issue?
Possibly, but VR should use linear for most games, so VR PP should work with it