Comment by threeseed

> but weren’t submitted by regulated financial institutions

This was detailed on an Apple support page for an app submission:

  Guideline 3.1.5 - Business - Payments - Cryptocurrencies

  Your app facilitates the transmission of a virtual currency but was not submitted by a corresponding exchange or recognized financial institution.

  Next Steps

  To resolve this issue, please provide documentary evidence demonstrating you have the necessary licenses and permissions to distribute an app with cryptocurrency exchange features in all the locations where your app is currently available.