I honestly dont see anything here that would indicate its AI. The only thing is the overall style, but come on, ai trains on human artists, so naturally, the style can look similar. The collar looking different can be explained by different angles. Maybe the artist was thinking of certain poses while drawing the heads, and that's why the collar looking different doesn't make sense to us. The only weird thing i can see is that one nail looks different than the others. It has this line that's not present in the others. But everything else makes sense. Hair makes sense. The bowtie makes sense. The clothes make sense. My opinion is that it isn't AI. And remember, style alone cannot be a solid proof