How does Sentinel check Blockchain? I've been very happy to hodl my Bitcoin on a paper wallet (coinglacier.org) and using Sentinel to view the balance of my addresses (using extended public key).

Sentinel is an awesome app, it provides just what I need and is very user friendly!

However, recently I was wondering, whether Sentinel was a privacy leak for me or not. So how is Sentinel scanning the Blockchain for incoming transactions? Is it using SPV, or is it just connecting to a server from Samourai, in a way that Samourai can tell which addresses I am looking after?
“Sentinel” is just an interface to an API owned by Samourai Wallet. It therefor leaks the fact that you own the outputs you’re watching are probably offline storage (and links them together into one wallet) when you watched them, and your connection details like your IP address and probable physical location.