In multiplayer, Beacon texture lights up when hit with diamond pick

Tried to destroy beacon, texture changed

When I tried to break my beacon on a iron pyramid with a diamond pickaxe in multiplayer, the texture changed to a lighter version.

Steps to Reproduce:
1. Get on multiplayer
2. Build a iron block pyramid
3. Place a beacon on top
4. Get a diamond pickaxe
5. Try to break the beacon, and the texture will change