have seen knock under load or boost etc. but what does it mean when the car knocks on throttle lift off ?

what happens at that moment and how to sort it

 

either fuel or timing or both just follow the load as it drops and draw yourself an imaginary line between the point where you lift off just before knock and just after and then reducing timing so the ramp up isn't so fast and increase fuel so the car doesn't spike lean if thats happening.