glowstone and quartzore textures when brecking flash stone textuer

i was in the nether on my minecraft realms getting glowstone when i noticed the texture changed to stone for a moment after it became an entity. i broke a few others and the same thing happened. then i tried doing it for quartz or and it did the same thing.

steps to reproduce
1. go into the nether with an iron pickaxe with an efficiency 1 enchant on it.
2. break either a glowstone block or quarts block.
3. watch closely.