The new blue planes in FlightRadar24 are flights that are transmitting GPS coordinates via satellite. These give a near-live position for planes over the open ocean (and some remote land areas), with delays of less than ten minutes.
This fills in areas of missing coverage, particularly near Antarctica, that the "Flat Earth" folk thought was evidence that southern hemisphere flights were being faked.
While it shows the (near) live position, it does not seem to show the historical track when you click on the plane. However, you can now see that planes do actually fly close to Antarctica - routes that only work on the globe Earth.