If I use experimental gameplay or education edition then sometimes every thing is black and purple(except items and mobs)

I like playing on education edition and experimental gameplay but if I use  one of those then this purple and black bug sometimes annoys me. I need to always guess what this block is when this bug is running. WHEN WILL YOU FIX THIS,MOJANG!?

Fix this ASAP or I’ll get more annoyed! Doesn’t affect items and mobs.

The pictures aren’t edited.they are real pictures!