That is such a catastrophically sad start to the new year. Looks like Apple lost a customer if they do not improve their screen to how it was with the X. They keep tweaking and tweaking. If an average customer can feel the difference, I wonder what Jobs and Ive would have felt. One of them is six feet under, and ought to be spinnin' like a high-speed rotational disk!
Now, that said, I assume you know that screens can look wildly different owing to the base color temperatures they are set at in factory and if True Tone is enabled or not, and even so, how True Tone is configured? If memory serves me right, 12/13 series had some issue with color temperature and True Tone, that might or might not have been resolved. Also, the 1,000,000:1 contrast ratio difference between the two (1,000,000:1 on X and 2,000,000:1 on 13) ought to make its presence felt, no? Plus HDR.