Is that local receipt validation, or server receipt validation?
I validate from https://buy.itunes.apple.com/verifyReceipt
My app only had a lot of downloads in the early days of release because at that time I had informed my community, but the highest was only 30-40 downloads. And then it averages about 1-2 downloads per day, which makes sense since I haven't run any marketing campaigns yet.
But recently there's been a strange sign like you see in the chart above, and it's all from refund:
Topic:
App Store Distribution & Marketing
SubTopic:
General
Tags: