"You have reached your daily chat limit" on minor account

on my Son's Child Microsoft account (age 14) in Microsoft 365 Family. Copilot shows "You've reached your daily chat limit. Check back tomorrow." after only a few messages and often immediately upon sign-in. Issue occurs in both browser and Android app. Family organizer account works normally on the same subscription. I asked my Copilot how to fix it and after several troubleshooting steps, it determined it is a child account bug and sent me here.