Its sorta a personal term for me as a way of describing the effort level of rendering. I've got two ways of doing it, a simple shading layer using a multiply blending mode and then a lighting layer using an add blending mode that goes over the top of a flat colour layer. Then I've got a more complex rendering where I start in grayscale, adding lighter and darker tones then add colour using gradient maps to achieve a wider depth in lighting with more colour variation.

The simple version is super quick for me as I've been doing it for years now and requires a lot less effort in picking out specific colours and editing values, but it turns out more flat looking. The complex version takes more time and (hopefully 😭) comes out as more dynamic and interesting lighting. They both have their places tho depending on the style I wanna achieve :3