Why, you're totally right. The base map is made by AI. After that go tons of editing, creating other maps etc. It is quite a standard procedure now, also time-consuming and stupid=(
Don't worry, thought, it is legalproof. (because Unity Asset Store somehow checks everything, and if it's not edited enough, they don't approve that).
To be safe: Vol 1-3 is true hand painted. Vol 3-34 and 49 and Stylized Nature and Dungeon Starter Pack are made in SD. Everything else made using AI. Basically, Mega Pack Vol 1 was made without using AI.
Please tell me, either you worried about legal issues or morality?