Learn how to increase the contrast in windows by turning off Allow Wallpaper Tinting in Windows on the Mac.
Apple introduced a new feature in macOS Big Sur that tints your windows based on the background. This is called Allow Window Tinting in Windows. It is a very subtle change, but in some cases it may make your Mac easier to read by turning this off. See what effect Allow Window Tinting in Windows has in this video for the Mac.
Video Transcript (video also has closed captions):