The Patriot system was designed ‘before’ hypersonic weapons were sent to battlefield and Raytheon has not said publicly that the is effective against a missile flying at hypersonic speeds (anything above five times the speed of sound). ....While the U.S. said that the Patriot system brought down last week’s Khinzal missile, it was not clear if that missile was traveling at hypersonic speed at the time.
The ballistic missiles that the Patriot has previously been used against are hypersonic too, so the speed isn't the only issue. The Khinzal is a hypersonic *cruise* missile. If the Russians weren't programming it to use its maneuvering capability to evade defenses while on its way to the target, the Patriot system could be expected to hit it as though it were following a ballistic arc.
[...it was not clear if that missile was traveling at hypersonic speed at the time.]
Wow! Russia produces some awesome “hypersonic” missiles...