ABPro uses the Legacy Checkout with Stripe which, I recently found, is not SCA-ready.
I am investigating but have no estimate of when, or even if, the Stripe implementation will be converted.
ABPro uses the 'Custom' integration method, not the 'Simple' one, so there is no quick fix.
"The legacy version of Checkout presented customers with a modal dialog that collected card information, and returned a token or a source to your website.
In contrast, the new version of Checkout is a smart payment page hosted by Stripe that creates payments or subscriptions. "
Recommend: Switching to PayPal, or different appointment booking system.