Apple has removed support for using an iPad as a Home Hub in its rebuilt Home app experience.
HomeKit allows you to remotely control compatible smart home devices, but some features like location-based automation require a designated Home Hub, which remains powered on and connected at your home when you are away.
When you leave your home, some thermostats can change the temperature to something more economical if you use a virtual geographic boundary. When you're away from home, a Home Hub can be used to invoke actions.
You can designate an Apple TV, HomePod, or iPad as a Home Hub in the current version of the operating system, but only Apple TV and HomePod are supported.
The iPad can still be designated as a Home Hub despite the change. It's likely that this ability will be removed in a later version of the software due to Apple's marketing webpage and interface notes.
There is still a Home Hub for the iPad in iPadOS 16.
Apple hasn't explained why iPad has dropped from the list of compatible Home Hub devices iniOS 16 but it could have something to do with Apple's announcement that HomeKit will support the upcoming Matter cross- platform compatibility smart home standard when the latter goes live.
HomeKit users will be able to integrate moreIoT device categories into their smart homes than ever before with Matter. The launch of Matter is expected to happen later this year, around the time that the public will be able to get their hands on the new mobile operating system.