How can I stop old passcode from working on Screen Time?

I’ve reset the screen time passcode for my sons screen time and he is still able to use the old passcode when he runs out of time and uses the “Ask for more time” feature from his phone. The old passcode works, and not the new one. However, when you go into screen time from settings and try to change any settings, when it asks for the passcode, the new one only works, not the old one. The old one only works when asking for more time. How do I fix this? I’ve already tried turning off screen time completely, then turning it back on and setting up from scratch with a different passcode. The old one still works! I’ve also tuned the phone off and on multiple times.

[Re-Titled by Moderator]

Original Title: Screen Time Passcode Not Syncing for Ask For More Time