Basically, the web traffic is routed through servers located in USA. The company *will* collect data: https://www.puffin.com/privacy
It is definitely much, much less than Google collects from you, so much is clear. It is your way of paying Google for their extensive and admittedly excellent services.
But in case of a subscription-based, secure browser, the option of jurisdiction-based servers should be built-in, paired with a zero data collection policy.