ConfirmationMethod = "manual"
I did the releaee with 'manual' too. I hoped than Stripe would use clear logic.
Customer put credit card, submit payment, verify 3D Secure and plugin will confirm payment.
But I got another result.
Customer put credit card, submit payment, Stripe shows the payment is correct and we csn confirm it, customer presses the button 'Confirm order', plugin confirms payment. And Stripe told me 'show customer the window for 3D Secure'.
It's strange but customer had to apply 3D Secure after confirming psyment.
I didn't understand this logic.
P.S.
You use nopcommerce onepage checkout.
If you use any one page checkour plugin you will not have this issue.
But I think I found the solution for nopcommerce one page checkout.
I can check what checkout method the store's owner use and I can did oen solution.
Please wait one day.