Hello,
Thank you for using the Apple Support Communities!
Based on the details shared, it sounds like you are experiencing an issue with Screen Time notifications on your Apple Watch. I'd like to help but I have a few questions.
-Are you referring to receiving a notification where your child is requesting more screen time?
-If you approve the request from your iPhone, does it allow your child's iPhone more time?
-Can you recall recent changes made to your Apple Watch or companion iPhone, since this stopped working?
I would like you to try restarting your iPhone Restart your iPhone, iPad, or iPod touch - Apple Support, and Apple Watch How to restart your Apple Watch - Apple Support, then test for the same behaviors again.
If you need continued support, reach back out with an update and responses to the questions above.
Regards.