Thanks for the advice everyone! I've changed the mouth shape, swapped to a "more expressionate" UV sphere for the eyes, added a bit more detail and that "slightly cross the eyes" trick really helped too.

Fortunately it was an easy fix and debris now spawns nicely overnight at a much more manageable and sustainable rate

"The dark side of game development is a pathway to many abilities some consider to be unnatural" 💪🦖

Thank you for your kind words! This is one of the first things I've ever drawn so I'm sure there's lots of room for improvement.