First, I apologise about the chat going crazy, the command block was to keep replacing the fungus so I didn't have to keep replacing the fungus every time. the command used was /setblock ~ ~2 ~ minecraft:crimson_fungus

I was using the default world settings, except for superflat, I turned on cheats, and I made the default gamemode creative.

This is a very minor bug, where if a fungus is grown and there is grass/ 2-tall flowers adjacent it breaks the grass/ 2-tall flower. It doesn't break blocks, as shown in the included clip. I'm not sure what else to mention, feel free to ask anything concerning the bug.

edit: this worked on both types of fungus