The Inclusion list only matters when the dismiss rule is Dismiss only selected apps. It then lists the apps that are dismissed. Notifications from all other apps stay in your panel.
Where to find it
Settings > Notifications > Inclusion list. The row appears only when the rule Dismiss only selected apps is selected.
Tip
If you want to keep a few apps and dismiss the rest, use another rule and put those few apps in the Exclusion list instead.