https://www.gamespot.com/articles/new-fortnite-blitz-mode-changes-made-heres-whats-d/1100-6457552/

Fortnite developer Epic kicked off the latest limited-time mode for Battle Royale, Blitz, earlier this week. Along with shorter match times, Blitz mode features significantly increased resources and loot spawns to quicken the pace of matches, although those will be seeing some changes soon.

On the Fortnite: Battle Royale subreddit, Epic announced it will adjust the abundance of building resources in Blitz mode with a hotfix update released on March 20. According to the developer, the rate at which players can acquire resources in the limited-time mode was "too abundant," and so the rate has been decreased in order to preserve a risk/reward element when players farm for them.