The InSight lander operated from 2018 to 2022, measuring quakes on the Martian surface. HiRISE continues to follow up on old landing sites like this (some even going back to the 1970s).
InSight landed in a dusty area and eventually was coated in enough dust to make it difficult to discern in HiRISE images like this one. The landing itself also blew dust off a larger area and that dark surface marking has gradually been fading away with time too.
We take these follow up images of InSight to estimate how quickly dust accumulates here. This helps scientists understand how young other surface disturbances like fresh impact craters might be too.
