The arrival of iOS 16.2 represents a change in the Home application which was supposed to improve its operation, but the issues ended up causing Apple to pull out.
HomeKit has undergone many changes in recent months, with more to come. Compatibility with Matter and the new Thread connection protocol are part of it, but the Casa application was also going to be the protagonist with a new architecture that would significantly improve its performance
Related article:
HomeKit, Matter and Thread: everything you need to know about the new home automation that is coming
To update to the new home, the first thing you needed was the new iOS 16.2 version (and the corresponding ones on your iPad, Apple TV, and HomePods). Once done, when you enter the Home app, a message appears informing you of the new update and asking whether you want to apply it or not. However, from the moment you accept the change, the suspicion that things will not go well arises.
Indeed it is so. Apple has acknowledged issues with guest users accessing your HomeKit network, even though they were already authorized. in my case for example all my guest users are gone
With all of this, Apple had no choice but to back down, and You can no longer update Home to the new architecture even if you are on iOS 16.2. Hopefully soon they will fix these issues and everything will be back to normal.