Exact figures may be classified - but physics isn’t. Air density reduces with altitude which means lesser lift and reduced engine performance as you go higher and higher so your initial hot rod performances start dropping off. Modern turbofans mitigate engine performance but they cannot magically create more air molecules at 30000ft to have them keep flowing around your wing pushing you up via newtons second law.With or without reciting the Divinely Blessed Battle Chant of the Fighter Pilot? Many of the exact figures of jets currently in service remain classified, and routine scrambles are intentionally toned down to mislead estimates of true wartime performance.