Please post a video of you doing following on your iPad Air:
-Pulling spotlight down and then rotating the screen
-Open Safari, activate split keyboard, then pull control center up
Not posting videos. I never use the split keyboard and the spotlight thing doesn't do much for me either. But I did try those two things mentioned and nothing bad happens.
However, there are always a a couple users that just have a tough time with a device. The vast majority do NOT so it's fair to say that the Air runs great on the latest OS for MOST people. If you are having trouble then go buy an Air 2.
Once again...that's the end of that.