In Stalker 2, navigating through dark areas can be a challenge. Fortunately, you can turn on your flashlight using a simple method. Press the RB button on Xbox or Tab on PC to activate the flashlight, and press it again to turn it off.
While turning on your flashlight can help illuminate the Zone, some areas may still appear too dark. To adjust display settings, pause the game and open the “Options” menu. Switch to the “Display” tab and tweak brightness, gamma, and HDR settings. However, be aware that increasing brightness might make the game look washed out.
Turning off HDR will enhance visibility, but it may also reduce the overall visual quality of the game. Remember, turning up the flashlight’s power won’t necessarily solve the darkness issue; adjusting display settings is key to improving gameplay.
For those wondering about the compiling shaders message popping up during gameplay, that’s a separate issue.
Source: https://www.gamesradar.com/games/fps/stalker-2-flashlight-too-dark