All attributes ending with _ are displayed as product attributes in the app. You can hide some attributes from showing in the app for all or some stores.
E.g. you have a store that sells expensive bags and a store that sells budget ones. You may want to list materials the bags are made from in the elite store only, even though both stores use the same attribute set for bags.
Use ~ for the store label to stop it appearing in the app when it is connected to that store.
In the following example only users of Elite and Preloved stores will see attribute Materials.