Banks look at your last 3 months expenses. A bank will just...

Banks look at your last 3 months expenses. A bank will just average what you have spent last 3 months and put it into living expenses. But then they do this for all your expenses to ensure you can afford to pay a home loan bank.
They may ask you to close down a liability eg Credit card etc if you can't afford to have both. But the choice is yours..close down the liability or don't get approved for the home loan.

This isn't a case of bank making consumers close down their BNPL so people use credit cards instead. Banks need to lend to make money however they need to be prudent in ensuring a consumer can pay the loan back.