Short answer: most likely just the lighting.
Long answer: MT3 and DCX have a different enough surface finish that the observed colors will appear different if the same material is used. Because of this, we use slightly different material colors to achieve the same (or as close as possible) observable color between the two profiles for comparable sets. These subtle differences and surface textures will also impact how different lights reflect and interact with the sets. So, it's primarily the lighting, but there is more to the story and color is a super fascinating rabbit hole to go down if you ever are so inclined.
HoffmanMysterFun fact... Disney Imagineers shifted the shades and hues of the colors used in Galaxy's Edge between Disneyland and Disney World to achieve the same perceived color because the two lands are supposed to be carbon copies of each other, but their N-S orientations are different resulting in differences in how the sun hits different structures at the same time of the day. That's some crazy commitment to the details.
Also interesting is the Pantone colors video that Linus Tech Tips did. Who would have thought that a successful business model would be to standardize colors?