I just got an iPhone 13 but I also believe there was an iOS update this past week. My old iPhone rotated with portrait lock off. Now it doesn’t rotate upside down. I like to charge it in the car and turn it upside down so the cord isn’t in the way.

I have an iPhone 13, with iOS 15.1.1, and none of my apps will rotate upside down when the phone is in that orientation. From what I’m seeing on various forums I’m guessing this “upside down” feature no longer applies with the newer iPhones.

Last iOS update was 2-3 weeks ago.

I've been using an iPhone 12 Pro for a year and just got my upgrade to the 13 Pro..

Neither of these devices rotate upside down.

I think rotation ability varies by app. But I don't think I've had the ability to rotate things upside down for a long time..

What was your previous iPhone model? (A Touch ID model such as the iPhone 6, 6s, 7, 8, or SE?)

Maybe it's the Face ID models that won't rotate upside down because of the notch? That would put the app switcher in an area that you couldn't use it.