https://voltage.cloud/blog/lightning-network-faq/lightning-network-privacy-explainer/
https://github.com/lnbook/lnbook/blob/develop/16_security_privacy_ln.asciidoc#attacks-on-lightning
https://abytesjourney.com/lightning-privacy/
"We identified 27,183 private channels, discovered hidden balances, and showed how a passive adversary can infer payment endpoints with very high probability."