Using swappers violates Epic Games' Terms of Service. Although some users have reported no issues, others have received permanent bans.
The (often found as Galaxy_Swapper_by_FrostChanger.rar or related to Galaxy Swapper v2) is a third-party software designed to let Fortnite players change the appearance of their in-game character to skins they do not own, such as the rare Galaxy skin, without buying them. Galaxy_Swapper_by_FrostChanger.rar
It changes the appearance of characters, pickaxes, and emotes only on the user’s screen, not for other players. Using swappers violates Epic Games' Terms of Service