Why is there a black box on the left side of my screen?

If a black or white box keeps showing up on the left side of the screen while you’re playing the game, this may be due to having both “NVIDIA Reflex Low Latency” enabled within the game settings and the “Performance Monitoring Flash Indicator” activated in GeForce Experience at the same time. To resolve this, you can disable the “Performance Monitoring Flash Indicator” in GeForce Experience.

How to disable “Performance Monitoring Flash Indicator” in GeForce Experience

1. Launch GeForce Experience and click “Settings.”
2. Scroll down and choose “Performance Monitoring.”
3. Disable “Always Show Reflex Flash Indicator.”