“Disable in-app purchases” feature is not working

Hello Hickdog27,

This page can help to confirm the needed steps to prevent in-app purchases: Prevent in-app purchases from the App Store - Apple Support

1. To turn on Screen Time, go to Settings > Screen Time, then tap Turn on Screen Time. If you already use Screen Time, skip to step 3.

2. Tap Continue, then choose "This is My [device]" or "This is My Child's [device]."

* If you're the parent or guardian of your device and want to prevent another family member from changing your settings, tap Use Screen Time Passcode to create a passcode, then re-enter the passcode to confirm. After you confirm your passcode, enter your Apple ID and password. This can be used to reset your Screen Time passcode if you forget it. 

* If you're setting up Screen Time on your child's device, follow the prompts until you get to Parent Passcode and enter a passcode. Re-enter the passcode to confirm. After you confirm your passcode, enter your Apple ID and password. This can be used to reset your Screen Time passcode if you forget it. 

* Make sure to choose a passcode that's different from the passcode you use to unlock your device. Learn what to do if you forget your Screen Time passcode.

3. Tap Content & Privacy Restrictions. If asked, enter your passcode, then turn on Content & Privacy Restrictions. 

4. Tap iTunes & App Store Purchases.

5. Tap In-app Purchases and set to Don't Allow.

If that's already configured as expected then it may help to try toggling off Content & Privacy Restrictions in Settings > Screen Time, restart the device, and re-enable it. After re-enabling it may also be beneficial to try toggling 'In-app purchases' to Allow, wait a moment and set it back to 'Don't Allow' to help refresh things.

Cheers.