Ivan Bogatyy writes in Response to lehnbergs article:
Right now, if Alice purchases Grin on an exchange and later uses it to shop on a darknet market, a sniffer node will capture a precise, undeniable trail of commitments (starting at the KYCed exchange commitment and ending on the darknet market) that incriminates Alice. Alice would not expect that, because she thinks Grin is “private” and further, public block explorers can’t show that link, only the special sniffer nodes can. This is the key point.
I consider this a serious issue, that being “no big deal” because it was known to some cryptographers all along is not really comforting.
In the Thread Why are you interested in Grin? many replies are about being interested in Grin because it’s “privacy”. Privacy is a key aspect of financial freedom, thus im glad to see that Devs like @david are addressing it ( Yo Dawg, I heard you like CoinJoins)