The release notes for that update were pretty thin, with OnePlus putting in the changelog that it was updating the handsets to Android security patch 2018.8, and that device owners could now confirm the entered PIN without tapping the checkmark. Other than adding that the software update would have a staged rollout over-the-air (OTA), OnePlus didn’t have anything more to talk about.
All in all, it’s good to see that even these again handsets are getting Treble support. Of course, the staged rollout for the new software should still be happening this week, so if you own either device and haven’t received OxygenOS 5.1.5 just yet, it should be arriving soon enough. With an extra bonus of Treble tossed in!