https://www.pcgamer.com/fortnites-boob-physics-are-an-embarrassing-and-unintended-mistake-will-be-fixed/

Fortnite Season 6 has arrived, and there's an awful lot going on. Backpack pets. Shadow Stones. 100 new cosmetics. But one thing stands out from all the rest: Calamity's new, um, moves. 

Calamity's new jiggle is not a sign that Fortnite is headed into Dead or Alive territory, (which recently committed to toning down its breast physics). Epic told me via email that the movement is a bug, not a feature.