I had a few times in a chat of where I had responses of being accused of being written by AI and I kinda found it offensive, but ignored it. but a few days ago had another one and then struck why I felt it. It is not being laughed at my poor attempts at being funny or such and being bad at something. (I'm used to that by now)
But being accused to be AI is basically saying you are not a human. You are nothing. not even an untermensch or an animal. a nothing.