http://walletdvl5avrmoxk2fwsf5b76zkmbkoo3r6kqeesq5hsgnq7xhbciad.onion/blockchain-attacks-on-privacy
This usually means that the user used the "send maximum amount" wallet feature to transfer funds to her new wallet, to an exchange account, to fund a lightning channel, or other similar cases where the bitcoins remain under the same ownership. Other possible reasons for sending exact amounts with no change is that the coin-selection algorithm was smart and lucky enough to find a suitable set of inputs for the intended payment amount that didn't require change (or required a change amount...