DIAGNOSIS This is usually a color format or range mismatch. Different inputs can sometimes default to different settings, and your source device might be outputting a limited signal.
FIX First, use the monitor's joystick to open the OSD. Go to Color > Input Color Format. Make sure it's set to 'RGB' for the USB-C input, not YPbPr. Then, go to Color > Color Space and set it to 'Standard' unless you have a specific need for sRGB or DCI-P3. Finally, on your computer (Mac or PC), check the display settings to ensure the output color depth and range are set to full or maximum.
IF THAT DIDN'T WORK On a Mac, go to System Settings > Displays and click on the Color profile. Try selecting 'Dell S2722QC' if it appears, or 'Apple RGB'. On a Windows PC with an NVIDIA GPU, open the NVIDIA Control Panel, go to 'Change resolution', and ensure 'Output color format' is set to RGB and 'Output dynamic range' is set to Full.
HEADS UP The USB-C connection carries both video and USB data, and some laptops apply different display profiles for different connection types. The monitor itself doesn't have different color calibration per input, so the fix is almost always in these software settings.