While storing the cached avatar images on your own server will take some extra disk space, the plugin makes sure that it does not grow out of bounds by deleting cached gravatars every other day and all other images once a week. When the cached file is accessed again, it is automatically regenerated.
If you don’t have to worry about the amount of disk space consumed, you can extend the maximum age of cached files via the filter hooks avatar_privacy_gravatars_max_age and avatar_privacy_all_images_max_age. The cron job intervals can also be adjusted via hooks (avatar_privacy_gravatars_cleanup_interval and avatar_privacy_all_images_cleanup_interval, respectively).
