To help protect against fraud, Chase sends us "tokenized" (virtual) account and routing numbers in place of the user's true account and routing numbers for our Auth product. Chase maps those virtual numbers to the actual numbers, so they work the same for ACH transactions. There's no discernible relationship between account masks and the tokenized numbers, so you'll likely never see a match between them. In other words, always present to your customers the account number mask, not the tokenized numbers from the /auth/get numbers object.
For more information on these tokenized numbers, please refer to Chase's FAQ or the "Chase Tokenized routing & account numbers" section of our Plaid Guide to Bank Migrations, which you can access from the Plaid docs.