I dropped iOS 9 support in the latest updates. Looking at the actual usage stats there are actually only 5 users using iOS 9,10,11 combined. Given all iOS 11 devices run iOS 12, and almost all iOS 10 devices ran 11, this makes sense. I am looking at only supporting iOS 12 and 13 in the next release. The primary benefit of this is it reduces the amount of testing needed as well as simplifies the code immensely resulting in fewer bugs and faster testing.
A lot of perfectly usable devices has support dropped by ios13 and iOS 12 updates still happen so those will likely stay around for a while (like iOS 9 did )