The `local_difficulty` debug entry is not shown when outside the vertical world boundaries

The bug

If someone is flying with an elytra above world height, they cannot see the local difficulty.

This bug report is based on MC-305445, which was resolved as Invalid due to having been reproduced in a modified version. This report adds more information regarding the issue and has no modifications used.

Steps to reproduce:

1. Set your game mode to Creative (or join a Survival world where you can safely get outside the vertical world boundaries).

2. Open the debug options menu (F3 + F6) and set the local_difficulty debug entry to "In Overlay" or "Always".

3. Go above 319 or below -63.

Observed behavior

The local_difficulty debug entry disappears from the debug screen once you move outside the vertical world boundaries.

Expected behavior

The local_difficulty debug entry would remain visible on the debug screen.