Archer;cavitation; look at the photos of any heavy prop job on a moist atmospheric day on take-off…

No, that’s condensation, a sudden drop in pressure which causes moisture in the air to change phase from gaseous to liquid.

Or listen to a Harvard/Texan!

And that is the result of local supersonic flow over the prop blades, which because of the sudden change in pressure can cause condensation.

Cavitation is the situation where the local pressure in a liquid drops enough to cause vapour bubbles to form, which then collapse.