This feature available in Android Tuner app manager allows to reset data file permissions to their default on selected apps. It can help if an app is dysfunctional. However it should never be used for apps that work fine. (If it ain't broke don't fix it)
If you fixed permissions on an app and it created problems, you can long-press the app in Android Tuner's app manager, tap 'open', tap 'open data directory', then long-press each file and folder and tap 'permission'. In the dialog tick all boxes, including the 'apply to sub-folders and files'. This may fix the problems caused. But there's no guarantee as the experienced issue may be caused by other things.