Tenochtitlán was never Mexico City. It was a completely different city that fell to ruins after the Spanish came. Later on, a completely different city was built on its ruins (not to be confused with rebuilt). Point is, just because they were at the same location did not mean they were the same city.
Thanks for taking the criticism well :). If you want to shorten your caveat, change it to "The city highlighted in blue is mildly controversial as to its origins". Then, change the color on the city to #0000FF on the design grid.
(It's ok i didn't know a lot of these either i looked them up