Expected: Beam to be rendered behind the beacon beam you are standing in, if visible at all.

Result: Beacon beam creates a cut out in the beam you are standing in.

1. Go onto nether roof for clear visibility.
2. Set up a beacon, of any size (with a base)
3. Move away from it until the beacon beam is just barely not visible behind the nether fogs.
4. Set up another beacon, of any size, where you are (with a base)
5. Stand in the beam of the beacon and look toward the other beacon

Additional info:

This works in different fogs (tested on soulsand valley, as well as crimson forest)

Attached is a screenshot. In the screenshot there is a beacon where the cutout is, as well as a beacon in between that and the one I am standing on, which renders normally.