Might have just found the biggest non-Large Biomes Mushroom Island ever!
Author: Garrrrrett
https://reddit.com//r/minecraftseeds/comments/j7vht9/might_have_just_found_the_biggest_nonlarge_biomes/
Seed: -1920330500010347390
Coords: -600, 1500
[View from the seed finder](https://prnt.sc/uv5mp9) (its massive lol)
edit: version is 1.16, although others have said it could work on earlier versions.