“It's a well-known fact that Nostr's NIP 04 DMs leak metadata. This seems like an obvious flaw, and has been pointed out as such many times. After all, if anyone can see who you're messaging and how frequently, what time of the day, how large your messages are, who else is mentioned, and correlate multiple separate conversations with one another, how private are your communications really?”
https://habla.news/a/naddr1qqxnzd3cxuurqv3sxqmrxwfcqyxhwumn8ghj7mn0wvhxcmmvqy28wumn8ghj7un9d3shjtnyv9kh2uewd9hsz9nhwden5te0wfjkccte9ehx7um5wghxyctwvsq36amnwvaz7tmwdaehgu3dwp6kytnhv4kxcmmjv3jhytnwv46qz9rhwden5te0wfjkccte9ehx7um5wghxz6gpz4mhxue69uhkummnw3ezuvrcx5czuar9vd5qzymhwden5te0wfjkcctev93xcefwdaexwqgjwaehxw309ahkvenrdpskjm3wwp6kyqgjwaehxw309ac82unsd3jhqct89ejhxqg8vdhhyctrd3jsygyhcu9ygdn2v56uz3dnx0uh865xmlwz675emfsccsxxguz6mx8rygpsgqqqw4rszfdfjx