Kylie Jenner's changing lips have long fascinated fans, but they aren't what people are talking about in her latest Instagram photo!

After months of followers commenting on the 19-year-old's Kardashian-sized butt, it appears as though the beauty mogul's ample behind has disappeared.

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"Big butt one day next day it's flat," one fan wrote, while another said, "Where [did] her ass go? Deflated?"

https://www.instagram.com/p/BMhjkBDlgbR/

The comments come just a few months after Kylie denied getting a boob job. "TMI but it's that time of the month lol," the reality star wrote at the time, blaming hormones for her chest's sudden increase in size.

She added, "They will deflate soon. And it will be a sad sad day." Looks like it happened to her booty instead!

Scroll through the gallery below for more attention-grabbing photos of Kylie Jenner's rear end.