The imitation was on spot, even in the ad libs and tone in the belts

Her pitch and ad-libs weren't amazing and there were a few miniseconds of off-keyness, but I appreciate how well her voice mixes up there generally ... Though her "whistle" (I think its just a high head voice) was very flat
Ariana was REALLY on point during the Yours Truly Era with this kind of thing, but now that she dances, sometimes shes a bit off and she makes up for it with her belts and 6th octave head voice in a not-so-healthy way; which is probably why she can't always hit those D-E6s recently.