There was a bug that could instantly kill you out of thin air. This was actually not something randomly it was your headset losing tracking and defaulting to the 0 0 0 position for a single frame and putting your character in a kill volume under the floor thus killing you.
When using the wrong openXR runtime this issue could occur more and on some headsets this could occur more as well.
This patch should fix this issue, let us know if it still encounters.
Make sure to verify your game files so you are sure the game was patched correctly.