When we restore a deck at lot of times there will be remnants of old sealer splashed on the vinyl from the last guy they hired or even the home owners themselves, though they seldom admit it. We always spay the siding with our deck stripper chem and it gets all the old stuff off and doesn't harm the siding. Sherwin Williams sells a deck stripper, I'd try that if the PVC cleaner doesn't work. Just don't get it on the deck.
Just wandering did you call the bozo back that did your deck? If he is a reputable contractor at all he will come back and take care of it for you.
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