Yuggs drop regular meat and fat when butchered.

[Dracque]

Despite looking even more mutated then giant worms yuggs give meat and fat which do not contain mutant toxins. Unless this is intended since it's a nether monster and not a creature native to earth which has mutated. Made a bug report since I'm not sure if it is meant to be this way or an oversight.

World's mod list. Message log shows which monster was butchered and the loot.

[Dracque]

Also happens without arcana. I apologise for not being thorough and checking if the issue could be reproduced in vanilla Bright Night before making the bug report.