Edit seems bugged, so im gonna write the edit here:

Eloquent is referencing parent_user in the sub-query but it isn't using it for the confirmed column. Anyone knows why eloquent is doing this or how I can fix this?

Why?
Probably because of the withPivot inside the childs().
How to fix it?
You could remove the withPivot, and instead of has('child') use

->whereHas('childs', function($shildsQuery){
    $childsQuery->where('comfirmed', '=', true);
})->...

You can also try make a scope for the confirmed column. Maybe it will work solve your problem.

Hello,

I have the same problem. Did you find any solution for this?

Thank you!!