Decoy flares do nothing against Radar guided missiles. You need chaff instead + even though the F-22 is stealthy the F-35 uses hundreds of radar receptors instead of one which means I can still see the F-22 from like 50 miles away.
Also since the radar missile is launched from miles away, you need to trick it with chaff because it travels at like Mach 3 with proximity fuse.