The phrase "leaked version" refers to information, such as a document, video, or photo, that was not intended to be made public but has been released without authorization. Full definition
If you're not sure how to find out your phone's model number, you probably shouldn't be installing leaked versions of Android on your phone. (bgr.com)
Along the way, you'll notice that the app is now calling itself «Pixel Launcher» — this is because you've just updated to the newer leaked version. (android.gadgethacks.com)
So it's not a final release, and I know many of you folks are using leaked version of the application now, but tonight you'll all have legitimate versions. (pocketberry.com)