I was wondering that but i believe it’s just filters being heavily used that looks awfully like AI. It would be AI if the structure of the buildings looked wonky, aspects of the building (windows, doors, details) were merging together or undistinguished, or the perspective of the buildings don’t look natural or cut off weird. But that’s just my guess
Be careful with the accusations. What exact panels and backgrounds do not look okay with everyone? Someone might be able to explain the angles or objects that don't look correct to you.
Heavily filtered real backgrounds have been a thing ever since, it can be a stylistic choice or because they're out of time. A lot of times, detailed backgrounds are harder to create than the main characters. Also, it's a basic filter you can find even in the most basic phones.
Somehow it just hit me now, but it seems Old Xian has been using AI/AI filters for the backgrounds for quite some time now. It's so sad to see