Well I missed a decimal point, thank you. My understanding is that zaps are a note kind, so its tracking those notes & values done over the protocol & yes its missing the zaps that are just lightning invoices.
Discussion
As I understand it (but i'm not sure if correct), note kind informs about zaps paid, but all* of them after all are just lightning invoices (*with exceptions). Nostr.band mostly misses these, that just doesn't see (private, obscure relays, info somehow not synced properly etc)