HI 🙌 there,
maybe you work it out already or found out the settings to change that.
Today I noticed that I was getting double notifications when I was paying with a bunq card via Apple Pay... both from the iPhone and from the Apple Watch.
For the notifications coming from bunq, there is the document that explains how to tailor them:
https://together.bunq.com/d/2901-how-can-i-change-my-notification-settings
Then there are setting for each card, both on iPhone and Apple Watch wallets that needs to be turned off if you do not need them, as myself, because I am getting already the notifications from the bunq App.
on the iPhone or Apple Watch
open wallet app

tap on the card you need
tap on the circled 3 dots on the top right to open the Apple Pay card settings

scroll to the bottom of the screen
toggle off (no Apple Pay notification for the card) or toggle it on to receive also the Apple Pay notifications

It is not a set up specific for bunq cards, but when you receive double notifications and the Apple Pay ones are on together with the bunq App you might think of a bug but it is all fine and can be adjusted with the above.
I hope 🙏 this was useful.
Maybe it can be added as a note on the document for notifications, just to inform there are additional settings.
have a great bunq day 🌈☀️
GG