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 :)