From my old hot rod days.

Valve float, this is when the valve fails to fully close before the next cycle. Since it usually only takes a very small amount to cause a significant loss of power it limits further RPM increases. It rarely causes damage.

Ring flutter, this is caused by several things but my experience was my first high performance rebuild, I either failed to check the fit of the rings inside the groove or did so improperly. The piston ring groove had widened past tolerances. This caused the rings to move excessively inside the piston. The extra flexure cause the rings to crack, poor compression and poor power. Rarely causes further piston damage. At least it didn't in my case. This can also happen when the engine over heats causing the groove to widen. Overreving can cause this though it is rare. If from overreving the piston can crack the piston but it is rare.

Rod stretch, I suspect this is the problem. The rod stretches from overeving. If it stretches enouth the rings contact the wear ridge at the top of the cylinder. This causes the rings to crack and often causes the piston to crack as well. Fairly common with overeved engines. Rods should be checked that they have not permanently stretched.