We just don’t include Spark information inside the lightning invoice. Unfortunately, there are still other ways to find that information outside of our control.

If you read the tweet thread, apparently you can track the transaction, for instance if you send a specific amount of sats and then check sparkscan, you can track and link it to the receiver

X (formerly Twitter)

Matt Corallo 🟠 (@TheBlueMatt) on X

@BlitzWalletApp Because I pay you 43 sats and then look to see who just received 43 sats in the last one second? Timing analysis is easy :)