I wonder if this is just a typo s/Teotihuacan/Tenochtitlan ?
Nowadays a significant portion of the lake Texcoco is absorbed in modern Mexico City.
This includes not only Tenochtitlan but also other cities in the Aztec empire like Tlacopan and Azcapozalco which are boroughs in Mexico City. But not all of them!
Teotihuacan and Texcoco, while nearby and connected in the same wider urban area are not part of Mexico City
Also worth mention: Teotihuacan was already an abandoned ruin almost 800 years before the Mexica (Aztecs) themselves rose to power.
And yet the name of the city is the one the Nahuatl-speaking Mexica gave it since the language and writing of the teotihuacanos remain almost completely unknown to us (and were unknown to the Mexica for that matter as well, although the Maya likely had some cultural memory of teotihuacan having existed as a society during both its period of dominance as well as that of the Mexica.