Can't erase iPhone without screen time pass code

Hi all. We don't remember having set up a screen time pass code on our iPhone. But screen time is turned on, and when we try to turn it off, we're prompted to enter the screen time pass code. We don't know it, so I've followed the instructions to erase the phone that have been recommended to everyone else asking this question in this forum.

But when I press "erase all content and settings," the phone asks first for my phone pass code (which I have) and then for my screen time pass code (which I don't). What should I try next?