Hey there, Chikapawouki
We understand that you are wondering why certain apps are showing on the Allowed apps screen and asking how to temporarily block apps. You are correct that you aren't able to add apps in Screen Time > tap the child's name > Content and Privacy Restrictions > Allowed apps. This screen allows you to allow or not allow the use of built-in apps or features of the device.
If you don't want your child or children to use any of the apps you mentioned at all, you can delete those apps off the device or devices, and then go to to Screen Time > tap the child's name > Content and Privacy Restrictions > iTunes & App Store Purchases and turn Don't Allow on for Installing Apps. That will stop those apps from being able to be downloaded and used again. You can change that setting whenever you'd like to allow them to download those apps. You can read more about that in the Prevent iTunes & App Store purchases in this article: Use parental controls on your child's iPhone, iPad, and iPod touch
If you want your child or children to still be able to play those apps, but with a time limit, you can do that in to Screen Time > tap the child's name > App Limits and edit those settings as you'd like. You can also set up Downtime on a device to limit screen time.
We hope that information helps. Take care!