Diagnosis
The monitor is likely using a non-standard preset or incorrect digital range (Limited vs. Full RGB).
How to Fix It
First, reset the color settings. Press the menu button, navigate to 'Color', and select 'Reset Color'. This reverts to the factory-calibrated sRGB mode. Second, check the input color format. In the OSD menu, go to 'Display' -> 'Input Color Format'. Set this to 'RGB'. Third, on your computer's graphics control panel (NVIDIA Control Panel or AMD Radeon Settings), set the output dynamic range to 'Full' if the option exists.
If That Didn't Work
The monitor may be in a power-saving eco-mode that limits backlight intensity. In the OSD menu, go to 'Others' -> 'Power Saver' and set it to 'Off' or 'Standard'. Then manually adjust contrast. Go to 'Brightness/Contrast' and set Contrast to 75% as a baseline.
Heads Up
The P2722H uses an IPS panel. Its inherent characteristic is superior viewing angles, but native contrast ratio (1000:1) is lower than some VA panels. Absolute black will appear as a very dark gray in a pitch-black room.