The confusing relationship between apps and iCloud

The relationship between iPhone apps and iCloud is very unclear.

If I understand it correctly, in Settings > Apple ID > iCloud (first figure below) I choose whether or not to enable the apps shown to sync to iCloud. The apps shown are just a few. All the apps I choose to sync to iCloud will not be included in the iCloud backup of my iPhone.

If I click now on Manage Storage, however, I see many more apps that were not included in the previous list but use iCloud Storage (figure 2 below)

So how did these apps end up in iCloud and what does their presence in here mean? More specifically, there are at least three confusing issues that I would like to be clarified:

1) Are these apps shown in here because they are synced to iCloud? If so, when did that happen? Why were they not included among the apps that I explicitly enabled to sync in the previous menu? Were they synced "behind my back"? (This is relevant for point 3 below)

2) Or alternatively, are these apps shown in here because they take up iCloud storage space as part of iCloud backups? If so, why is their storage space shown independently and not included in the overall figure for the backup?

3) Whether case 1 or case 2 above is true, it seems to be relevant for what happens when I uninstall and reinstall one of these apps. Suppose for some reason an app is malfunctioning on my iPad and I decide to uninstall it and reinstall it. When I uninstall it, its local data is deleted. If the app is not synced to iCloud, I can retrieve its local data in the iCloud backup of the iPad and restore it after reinstalling the app. However, if I uninstalled the app without realizing it was synced to iCloud (because it had been synced "behind my back", without asking me explicitly) will I find its local data in the iCloud backup? If not, I just deleted its local data from all the connected devices: my iPad, my iPhone and my Mac. This would be a really bad design, unless there was some safety net analogous to what happens for Photos. In the case of Photos, in fact, the user has a 30-day grace period to recover a photo deleted from iCloud. Is there a 30 days grace period as well to recover local data after uninstalling an app synced to iCloud before it is lost forever? If so, where can I find this copy of the local app data and how can I restore it?

Thanks in advance for all the clarifications.