Jumping Bug Causes Gravity Reversal

## Description
There is a known bug where attempting to jump occasionally causes gravity to reverse or behave incorrectly, resulting in unpredictable player movement.

## Steps to Reproduce
- Attempt to jump under certain conditions (exact trigger unclear)
- Player experiences inverted or reversed gravity behavior

## Expected Behavior
- Jumping should consistently apply upward force and return the player to normal gravity

## Status
- Known issue (acknowledged during submission)

## Notes
- Likely related to physics, gravity scale, or state transitions
- Should be investigated before any future polish or expansion

Look at the player movement and physics scripts, likely involving gravity scale or state transitions. The exact trigger is unknown, so start by reproducing the bug under various conditions. Check Unity's physics settings and player controller logic. 'Done' means the jump consistently applies upward force without gravity reversal.

Written by the indexing model from the issue text.