Sudden authentication for Google (in app) purchases?

I’m a bit confused. I have both a Samsung (main phone) & an old iPhone (backup phone).
I’ve been able to download paid stuff from the App Store no problem. And until recently from Google Play too. But maybe since the beginning of '21, I’ve had to authenticate almost every in app purchase made on the play store (I also assume this would happen if i purchased TV shows or paid apps or music etc on Google Play as well) with my PIN.
I could understand if it was a large amount of money say in the hundreds (although I just bought a designer handbag online and didn’t have to verify with my PIN) but it’s usually in app purchases in the region of £5-10.
Has anyone else had this issue?
What do you think the reason is?

In the ‘Play Store’ app on your Samsung device, in ‘Settings’, do you have ‘Require authentication for purchases’ set to ‘For all purchases through Google Play on this device’?


Nope. It’s set to never require authentication for Google Play purchases. Even if it was switched on, I was under the impression that would be my password instead of fingerprint, rather than manually authenticating it with my Monzo PIN every time?

Is ‘Authenticate with biometrics’ enabled in the Monzo app (Settings → Privacy & Security)?

I’ve got a feeling your card has been added directly to Google Play.

If you add your card to Google Pay instead you’ll be able to access it within Google Play and it shouldn’t require your pin. It may ask for your fingerprint occasionally instead but you shouldn’t need to approve the payment in the Monzo app any more.