The Snowy Adventure Cape and Crystal Falls Cape of the new Winter Spotlight event both use the incorrect attachment type, causing them to behave incorrectly compared to other items like them.
Compared with Royal Cape - KSI, a different cape item uploaded by Roblox.
When viewing these items in the explorer, you can see that they both use “RootAttachment”, causing them to follow the whole body instead of the back of the top torso. (Which would be “BodyBackAttachment”)