I'm not sure!
1989 is still very Taylor but Bad Blood sticks out as the one song that is maybe not so characteristic of Taylor. It would be very genius if that was intentional.
On the other hand, it just seems to be a broad song which Taylor happened to relate to hers and Katy's "bad blood". Lyrics like "Baby it used to be mad love" make me think this song was (is) intentionally written as a break up song, but like I said, Taylor could relate to it personally because of what happened.
I really don't know, and I guess we'll never know either! Absolute KII if it was deliberate and Max Martin helped scalp Katy.