Yeah, it could be a problem if the user is making or receiving a LOT of payments, in reality I’m not sure this will be an issue. If the kind is not encrypted it’s a bit less private and less consistent with the current NIP-47 spec (although more nostr-like).

Maybe it’s possible to go this way for now and make dedicated event kinds in the future if it does become problematic?

Thanks for your thoughts! I’m happy with both options.