Quite impossible to "fat-finger" it.

EDIT: Maybe it's a discrepancy about what a "confirmation" is? If the author of the twitter thread is correct, the "confirmation" is just a large button on the screen that doesn't require password re-entry, which is not much of a confirmation. He proposes that it's easy to accidentally spend the money if you go to the "upgrades" screen, then put the phone in your pocket without locking it.

Making a conscious purchase and then regretting it (after getting yelled at by your wife) does not equal to a "fat finger incident".

As requested: https://imgur.com/a/1IYTbrc

Notice how the payment transaction actually happens in Apple Pay. So that means that you need FaceID to complete it. Impossible to do if the phone is in your pocket!

I believe the route to the accidental purchase the twitter thread refers to is through the "Pay with credit card" button though, which for some reason isn't present in your configuration.

https://twitter.com/tedstein/status/1219406791941017607

See bottom, under the "Apple Pay" button.