Photos of aircraft on Flightradar24 are not hosted by Flightradar24 but come from the separate JetPhotos catalog. 

The latest photo available for that registration in the JetPhotos catalog is shown when selecting an aircraft of Flightradar24. In some cases, registrations are reused and there may not be an updated photo immediately available on JetPhotos. 

You can help make sure all photos are up to date by submitting your aviation photos to JetPhotos. 

Learn more about uploading to JetPhotos.