look at OG nostr DM's. understand what you're leaking there. similar concept. timing. link analysis. node analysis with common edges and clustering. traffic flow analysis. combine several of these and you can paint interesting social pictures and activity histograms. oh, timing with IP, ie. he hits off this IP most of the day but then this other one during the evening, which can deduce pattern of life. link sharing for previews that have UTM's attached. probably many many more.