Why was my bank account charged by Stripe?
Each payout from Stripe reflects your available account balance at the time it was created.
In some cases, you may have a negative account balance. For example, if you receive $100 in payments but refund $200 of prior payments, your account balance would be -$100. If not further payments are received to balance out the negative amount, Stripe creates a payout that debits your bank account.
Read more on this here.