Color changes of parquet floor is usually observed in the places which are least of all exposed to sunlight. For example, the parquet boards under the carpet can be darker. However, if you remove the carpet, over the time the floor color becomes even.
Every wood species has its own specific color that depends on the amount of wood resin it contains. UV radiation which is a part of sunlight changes the color of parquet boards. Some wood species are darkening over time while others are getting lighter. The parquet color change depends on amount of daylight and natural wood features. As a rule, the strongest changes happen within first year after installation.