Where is the App Compatibility screen now??

I reached back in my memory, and the reason there was a compatibility listing in iOS 10 was because iOS 11 would be the first 64 bit iOS version, and apps had to be recompiled to run in the 64 bit environment. The list was for those apps that had not been. There has not been any other compatibility issue like that since. The current issue is that many developers do not continue to support older versions by choice. There is no reason they can’t, only that it is not worth their while to support the different versions that would be required.

About the only apps now that are not compatible with the latest version are those that have an external hardware component that either won’t work with the enhanced security of the latest version of iOS or that need to be updated to work. That’s very few apps; unfortunately, some of them answer a critical need, such as medical accessories (e.g., blood glucose measurement). If you have such a device you need to check with the manufacturer.

There was a one-off case with iOS 14: HomeWerks bathroom fans that had built in Bluetooth speakers stopped working with iOS 14. The cause was a bug in the Homewerks Bluetooth firmware that broke when the iOS 14 updated its Bluetooth support. Homewerks dealt with this by replacing the fans, as the firmware could not be remotely updated.

Hey there Timothy Arends1,

You can still see app compatibility information from the App Store. Tap the app in question and scroll down to the "Information" section. You may need to click a dropdown to see the detailed compatibility info.

This page has details: Get apps in the App Store on iPod touch

Take care.

Timothy Arends1 wrote:

I simply will no longer upgrade my devices if I have no easy way of knowing which apps will be broken in the process.

Ok, so you are perfectly willing to leave your device exposed to security vulnerabilities if Apple doesn’t do what you want. That’s fine. Just understand the consequences of your decision. If your iPad Air is original (and is 8 years old), and still on iOS 10, then it can only be updated to 12.5.5 anyway, and it is too old to run most current generation apps.

You can go to the App Store and read the supported iOS versions for each app that you have.

Timothy Arends1 wrote:

But there's still a need for the App Compatibility screen. As long as any app may simply stop working on a new version of iOS, as frequently happens, there should be some warning mechanism so that a user can extract any data from the app before upgrading, as well as to make an intelligent decision on whether he wants to upgrade or not.

You can let Apple know what you'd like to see here:

Product Feedback - Apple

Timothy Arends1 wrote:

Keeping track of which apps on your device are still in development is kind of important if you plan on updating your device’s OS, since apps that you store important data in may no longer run if an app is no longer compatible with the new OS.

On iOS 10, you could see a list of apps that were no longer being updated by going to Settings > General > About > Applications.

On iOS 14, you can still go to Settings > General > About > Applications, but tapping on Applications no longer brings up the App Compatibility screen; in fact, it does nothing.

The App Compatibility screen is playing hide and go seek again! Where is it off to now??

That wasn’t a list of apps that weren’t being updated; it was a list of apps not compatible with the next version. Apple has no way of knowing whether an app will be updated in the future.

There are no apps that stop working on a new version, except for the few hardware-dependent apps I mentioned, and apps that have been abandoned by their developers. And with over 1 million apps Apple can’t keep track of abandonware in any practical sense. The list for iOS 10 was generated by code on the phone that looked for 32 bit libraries, but there isn’t anything to look for in an app that has been abandoned.

And the only intelligent decision on upgrading is deciding if you want your phone to be secure from malware or not. In particular, iOS versions 12.5.5, 15.2.1, 15.3.1, and 15.4 all fixed some really serious vulnerabilities; 15.2.1 in particular protected devices from NSO Group's Pegasus spyware.