A workaround I found is that if you search your kids name in spotlight (not the contacts app) the ask to buy notifications will be there. And you can approve/deny in the absence of a notification.
That's good to know. Thank you!
I said above that it only happens rarely. Not anymore. Now I don't get any notifications for my little daughter anymore, and it's been like this for about a week already. It stopped working altogether. Strangely, this only happens for her, not for her sisters. Her sisters' notifications still arrive as expected.
Restarting her phone, as well as my phone and my computer, which previously used to fix the issue, didn't change anything this time.
I had to go to the family settings, disable the ask to buy feature for her account, wait for her to install the app, then enable it again. Really annoying.
Not receiving the notification wouldn't be a major problem if I could still see it somewhere (e.g. in a 'pending actions' menu in the App Store app, or something like that). Your workaround seems to be just what I need. I'll try it next time. Thanks! 🍺