Summary:
Beacon beam disappears at Y = 321 in the world.
The problem is that if you place the beacon at the maximum height (320 height), then its beam will be present only inside the beacon, that is, it will be practically absent. Screenshot attached*
This also breaks parity with Java, where the height of the beacon beam is not limited!

Steps to reproduce:

1. Build a 3x3 diamond/emerald/gold/netherite/iron platform at 318 height.
2. Place a beacon in the center (at 319 height).

Observed results:
The beam is visible only inside the beacon block.

Expected results:
The height of the beacon beam will not be limited.

Screenshots: