Per the Refund Processing Agreement, you authorized TurboTax to debit your bank account if your refund was insufficient to cover your fees:

In addition, by clicking the "I Agree" button below, you electronically sign and authorize Intuit (through its third party processor) to debit the TurboTax Fees, Additional Products and Services Purchased and any applicable sales tax from your bank account number identified in the Agreement below, in the event that you do not receive a tax refund that is sufficient to pay for them.

Why was my bank account auto-debited for TurboTax fees?

https://ttlc.intuit.com/community/charges-and-fees/help/why-was-my-bank-account-auto-debited-for-tur...