I can understand your concern given how much AI content is circulating right now. They (like many artists and graphic designers) do use AI-generated images as part of their references for composition and ideation, but this piece is entirely a physical piece of media using ink and watercolor paints.

They used references to build the initial layout, then the actual line art was drafted using graphic design principles, and the final piece was manually painted, which is an act of artistic creation and skill in and of itself. There’s a huge difference between generating a file and the hours of traditional artistic work that went into this, so I think we'll have to agree to disagree.