Might be color subsampling or HDMI limited range. Or a broken ICD set. Or something completely different.
Please check the color profile set. Please run nvidia-bug-report.sh as root and attach the resulting nvidia-bug-report.log.gz file to your post.
Please try clicking on the “SONY TV *00 Monitor” line at the top, then Add Profile, and then selecting “Colorspace: sRGB”. That will override the color calibration settings from the monitor and disable the color adjustments.