The linked page already says that it reports on the constellation, not just GPS: "The map uses are color coded overlay to indicate low (green) to high (red) le

The linked page already says that it reports on the constellation, not just GPS: "The map uses are color coded overlay to indicate low (green) to high (red) levels of interference with global navigation satellite systems (GNSS). Often just referred to as GPS, there are actually multiple systems beside the US GPS constellation, such as Russia’s GLONASS, Europe’s Galileo, China’s BeiDou, and others."