iOS in app payment/subscription via Plaid ACH?

I came across a very popular financial iOS app (top 100 in the US) that uses Plaid to connect to the users bank account. They use this connection to give the user financial alerts/analysis and sometimes loan money.

While testing the app I noticed they offer a premium subscription to get access to more sophisticated features. I clicked the sign up CTA expecting to see the native iOS app payment/subscription confirmation prompt appear, but it didn’t. I brushed it off and thought there must be a bug. The next day I see I’ve been charged for the premium service, but not via Apple. It seems to have been done by an ACH transfer via the Plaid connection. 

My question is: is this allowed by Apple? From my research, any type of digital subscription payment must go through the standard Apple in app purchase flow. Am I missing something? Seems very shady to me.

Here is an example of another app that does the same thing - when you go to link your bank account via Plaid, they sneak in a monthly subscription authorization that will take place via ACH. How is this allowed?!

Qapital banking
iOS in app payment/subscription via Plaid ACH?
 
 
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