Player falling down after post processing turned on.

So when I turn on post processing by a button in the game and then I click "Play" the character starts falling down. The floor has mesh collider and my character has box collider and rigidbody components. After I click "Play" I set the player's position to be above the floor but still, the character SOMETIMES seems to teleport under the floor/ground and then sometimes teleport to its start position set in the code as I mentioned above. This weird behaviour is more likely to happen when I click the button which turns on post processing more than 1 or 2 times so It seems that spamming the button makes this behaviour more possible to happen. Also I checked the code and there is no line which tells to set the player's position to anything. I only set the player's postiion after the "Play" button is clicked. How to fix this post processing "bug"?