That‘s not how direct debit works. There is no accountholder involvement with processing direct debits, but they can be easily reversed (although after the fact).

There are related payment schemes though that do initiate a push payment (i.e. SEPA credit transfer), giving the accountholder control over the amount and payee, but they are not yet as ubiquitous or usable internationally.

That is exactly how my debit card transactions works. When I buy a game on steam using my debit card I get a popup in my phone asking if I really initiated the payment and lets me decline.

The payment page spins until I click ok on it in the phone, since my bank wont accept the transaction otherwise.

The grandparent post was asking about the German payment system, which presumably refers to SEPA Direct Debit, not debit cards.

What you are referring to is called 3DS, and it's a feature of both credit and debit cards. (It's available worldwide, but most commonly used in the EU, since it's mandated for ecommerce card transactions in many circumstances.)

It also only happens for higher-value transactions here. I don't have to authorize every tenner unless it's the 10th in a row or something