This might have to do with the new 3DSecure payment approval. If set to yes, a notification will popup to confirm the payment. If set to no, it will probably use the old auto-approval system. Just a wild guess.
I don’t have this option but I see the 3D Secure payment approval.
Before we have to speculate further, maybe can explain and document this in the help system.
Maybe Revolut have no clue either
ps. I find a bit strange that beying fintech there is not 1 dedicated person in Revolut whos job exclusively would be to answer all questions their users have here in forum. Some staff members answer time to time, but it feels happening less and less often lately.
Sometimes it’s too simple to ask the support. In general:
It’s mainly to prioritise push notification since user where complaining that they don’t receive push notifications after switching the device
Also in case you don’t have a phone signal, but you want to make a bank transfer for which you need a code, they will send it via wifi if “Trust this Device” is checked.