https://www.gamespot.com/articles/new-pubg-limited-time-mode-now-available-on-pc/1100-6457822/

The next limited-time game mode in PlayerUnknown's Battlegrounds is now underway on PC. This weekend only, players will be able to take part in the flare gun event, which runs from now until 7 PM PT / 10 PM ET on April 1.

Flare gun mode is set on the desert map Miramar, and as its name implies, it introduces the new flare gun to the loot you can find in the game. Developer PUBG Corp. says only a "limited number" of these will appear in the mode, and they'll spawn inside certain single-story houses across the map.