https://www.gamespot.com/articles/fortnite-hunting-party-challenge-week-3-secret-bat/1100-6462460/

Week 3's challenges are now available in Fortnite, giving players across PS4, Xbox One, PC, Nintendo Switch, and mobile devices another opportunity to earn Battle Stars and unlock some more Season 6 rewards. As usual, if you manage to complete all of the challenges from a given week, you'll in turn complete a Hunting Party challenge, which will reward you with a special loading screen pointing to the location of a free item hidden somewhere around the map.

Typically, the item in question is a free Battle Star, which levels your Battle Pass up by one tier when collected. However, toward the end of Season 5, Epic began offering free battle banners--items that players can use as their profile icon--as a reward as well. It seems this season, Epic will alternate between the two; Week 2's Hunting Party challenge led to a battle banner, but this week, players will once again be able to collect another free Battle Star--provided you're able to complete all of the requisite steps.