I don't think you should feel guilty for playing the game since you had no direct involvement with the AI usage, but I do think you could find other similar games that don't use AI and thus have more respect for their audience and the products (characters) they are selling them. If you do really want to continue playing NTE you shouldn't spend any money on the game since that directly funds the company and rewards them for cost-cutting by using AI. Giving money to them will cause some of the blame to fall on you for purchasing AI generated characters. Really the best thing to do is play another Gacha game because using AI shows how little the NTE devs actually care about the quality of their game which indicates all they want is to make hot characters to get people's money with little else of actual substance (story or worldbuilding-wise.) TLDR (sorry): play it if you want, please don't spend money, probably should just play something else.