New release and new great feature. Starting from version 1.75 when using Hooks option you can generate and display all currently active display hooks.
Just open the plugin settings page, scroll down into the Hooks section and click on Show current hooks button inside the table. After this you will see all hooks and plugins are currently using to display product labels.
This feature is very useful if you want to modify current hooks to customize labels position but you don't know exactly what kind of hooks the plugin uses.