Plaid does have products that do request bank credentials, but those products are not used for age verification. It's very common that a given customer-facing flow will use multiple Plaid products together to handle multiple different customer needs, so it's likely that the flow you were working with was using multiple Plaid products and requesting bank credentials, but for a different reason than to perform age verification (for example, KYC + bank account ownership verification or KYC + bank account validity verification).