on Lightning, there is a unique ID attached to any payment

anyone on the path knows the amount of the payment and the payment ID, and which node it is going to and coming from

using certain heuristics, it is possible to identify recipients, and senders with high accuracy, by only controlling some of the nodes on the path, which can be achieved by well funded chain analysis entities nostr:note1k6zvw7rg3dv8mcmzgn9w0k90g95y8mw04tftm25ke2htfpkmutyqe0h3kr