Not sure if it's AI, but there definitely seems to be something fishy going on here. Look at the lines for the hand and how their chests sort of blend together. It reminds me of those filters that were popular a while ago to make photos look like drawings. The artist's other tweets using the same style like twitter #1601760216143388672 seem to have the same line issues.
Looking over their twitter, the sketch's lineart is the artist's own and consistent with earlier work, but definitely not the coloring. Looks like img2img completion from the sketch, which'd make it AI-assisted.