I haven't done extensive testing, but I know Brown Mushrooms act weirdly around fire, and I don't believe this is intentional.

In the video I attached to this report you see me perform two actions:

• In the first part, you see me placing mushrooms on some netherack in the nether. In the middle of this square of mushrooms, I light that block on fire. Nothing happens until I then extinguish the fire, and when I do all adjacent mushrooms (even the diagonals) break along with it.
• In the second part, you see me lighting some netherack on fire and attempting to place mushrooms around it. However I can't, and it isn't just all the adjacent blocks, it's more of in a circle shape where I can't place them.

Further testing will need to be done to see what other blocks are affected by fire.

(Nvm just going to link the video to a streamable page since there is an upload size limit, but it's otherwise the same video)

https://streamable.com/9jpwdj