How to restrict messaging or #images on child iPad?

My daughter has been finding objectionable content in gifs using the #images option in messages. I need to prevent her from accessing #images or the whole iMessage app.

Every solution I find to do this is from an older OS version that doesn't work anymore. (She has iPadOS 18.2.1.)

I have the message app set in Screen Time > App Limits, but the minimum time is 1 minute per day, so she can still get into it and peep at it.

Uninstalling it from the iPad isn't an option. iMessages can't be uninstalled and I see no way to remove #images.

I can't deny iMessages under Content & Privacy Restrictions > Allowed Apps and Features because it's not there. (FaceTime is there, but not messages.) I don't see messages anywhere else except App Limits (which has that 1 minute minimum).

I can't even remove all contacts, because she can still open a new message window, not fill in the "to" field, and still browse images that way.

If there's really no way to do this, this is a HORRIBLE hole in parental controls. I am going to have to take her iPad away completely if I can't fix this. She is swearing at her classmates and giving inappropriate gestures, and I'm 95% sure she's getting it from #images in messages.