I think my dad's phone has been AI jacked

So I called my dad and I had a conversation with him for about an hour and a half and I believe that the conversation was with a bot and I don't know how to prove this other than some things were just slightly off based on our shared experiences and the humor that he used to have isn't quite there but he's also older and I don't know if it's just because he's old now it's weird because I don't know how to tell and I think the models are good enough that they could do this if they wanted to