I think that is gonna be the main hook, it's the trademark "Oh's" he has used in the past.
It sounds good though to me, I like her fun pop songs. Idk why people are on the defense trying to act like she was going to do some crazy harsh EDM track or go and pull an Adele with a ballad. You had to expect this kind of song from Katy, and she did well with it
I'm getting Here's To Never Growing Up teas from that snippet.
Glad I wasn't the only one, was the first song I thought of tbh. Doesn't sound exactly like it, but they're both similar in using an "Ooh" sound during the chorus outro (I'm assuming what we got is the chorus outro).
Have we confirmed the producer by the way? I'd be really surprised if it's not Dr. Luke.