What traffic data is openrouetservice using for calculating isochrones?

Hi everyone! If I create a map with isochrones measured in 5-minute intervals from the airport using the open source service, what traffic data is the open source service using for this calculation?

This made me wonder since it is different to drive to the airport at 8am in the morning on a Monday than 1pm on a Sunday.

My idea is that it uses the traffic data that it has at the moment of generating the isochrone, for which, if i wanted to know the isochrones to get to the airport on a Monday at 8am, I would have to calculate the isochrones on that same day and time to receive the information I need.

Please let me know if you have any idea, it would help me lots!