We don’t know exactly why the cities were abandoned
Although the exact reasons are unknown, archaeologists estimate that the city of El Mirador was abandoned for about 700 years. It was inhabited after the Late Classic and Late Terminal Classic period, but the structures were not repaired, nor were new constructions made at that time.
The case of abandonment in Tikal is quite similar, the reasons why the city stopped working are not yet known. Many assume it was displacement or war, but there is no evidence to support these theories.