Trying to set up Account Recovery Contact, and I get the message that I have to remove my iPad Air from the list...why? I still use it.

What version of iOS is your iPad Air running? Does it meet these requirements:

• All of your devices must be running iOS 15, iPadOS 15, watchOS 8, or macOS Monterey or later. You might be prompted to update any devices not running the latest OS, or remove any devices that you aren't using.

If it's an older iPad Air and not capable of running iOS 15 or later, you will need to remove it. If it is capable of running at least iOS 15, update now and it should be fine.