So this isn't a question but an answer.
I was having problems removing my child's account from one family to move to another.
The issue was I wasn't able to remove consent from my child's account.
I kept getting a "there's a temporary problem" like below.
What I did to get around that was the following;
Sign into the child's account.
Edit Profile
Change the birthday to an age over 18 ( don't worry, you can change this back later )
save. sign out
This will automagically remove the "consent" flag on the child's account,
Sign in again and change the birthday back, save, sign out.
This boggled me for a few weeks, and solved this on my own while I waited for the Microsoft support to connect
thought I would share.