I recently began getting a notification that sounded suspicious, mainly because of the awkward grammar, and the fact that I use Avast Cleaner which notifies me of temp files and cached files that can be cleaned. I googled the phrase "junks found" and discovered ES File Explorer was the culprit.
From Android Central posts on the subject:
ES sends data in the background to the developer's China based server so they can sell it to ad companies. I didn't see overt ads yet it was still collecting data for sale. They just chose to do it in the background rather than opting to display open ads.
There are a number of complaints about it in the app's recent reviews
There's a Reddit thread on this topic
So, even though I have recommended this app in the past, I have uninstalled it, the notification went away, and I will try some other file manager app - File Explorer - Android Apps on Google Play is one that is recommended on the Android forums.