I don't use that app, since I'm no longer on iOS (thank goodness!), but I heard something about apple not allowing apps in its app store to handle any sort of payments (sats or other) without it laying its grabby little paws on part of the money being transacted.

I heard there's like a trick you have to do that modifies iOS nostr app(s) to turn on the zapping functionality, becauae they have to have it off out of the gate so that the app store doesn't kick them out.