PNC Bank says that this is the cause of new security procedures which have the effect of limiting Plaid's ability to verify customer Routing and Account numbers.
While I'm not a customer of PNC I think this is actually a good position for PNC to take - there is a ton of ambiguity in the data that Plaid collects on customers who may only think they're verifying their account for an ACH transaction.
Plaid's business in not necessarily deceptive but it is far from clear to the end user about the extent of their data collection.