Oh I think I know what you're talking about, abusing a minisplit by idling the inverter back too far. Effectively you have a hugely oversized condenser for the tiny flow, under the right conditions like a cool night you can get ridiculous subcooling.

But COP is irrelevant in this case because you've derated the actual BTU to near zero, you aren't moving any refrigerant.

Also yes this will kill your compressor because the minimum speed is set where it will get enough oil flow. Run it too slow, and it won't pick up oil and eventually seize up. You also could end up running the suction in vacuum which is also hard on compressors.