https://www.gamespot.com/articles/fortnites-high-stakes-challenges-out-now-heres-wha/1100-6461538/

One of the big new additions to Fortnite in an event called High Stakes. It is scheduled to be one of the last major surprises in the game's fifth season and developer Epic Games has detailed what players will have to do to complete the High Stakes challenges and earn its rewards. [Update] The High Stakes challenges are out now. They were introduced as part of Fortnite update 5.4 and you can read the full patch notes for that here.

Like the new limited-time mode, Getaway, High Stakes is themed around heists and tasks players with stealing, killing, and escaping. The first part of the challenge offers up 5,000 XP to anyone that plays 10 matches of Getaway. If you're able to deal a total of 500 damage to opponents carrying the coveted jewel, you'll also get a special spray. Those that manage to pick up a jewel in five different matches of Getaway will get a special skydiving trail that features money flying off your character. Finally, if you complete all three of those challenges you'll get a crowbar skin for your pickaxe.