Whenever you activate a beacon (doesn't matter if it's fully charged or not) the block itself doesn't emit a light beam into the sky.

How to reproduce:

1.Place down 9 blocks of iron/diamond/emerald/gold/netherite in a 3x3 shape.

2.Put a beacon block in the middle.

As you will hopefully see it won't show the beam of light but the beacon itself will actually work.