Apple has decided to change the HomeKit architecture fundamentally with iOS 16.2. However, instead of better performance, the upgrade caused problems for some users, and Apple backed off. The option has reappeared in the current beta of iOS 16.3.
The architecture upgrade released with iOS 16.2 is optional. Interested users should benefit from optimized device response times, as well as better stability. In addition, the upgrade is supposed to be a prerequisite for future features.
However, the upgrade was already no longer possible shortly after the release of iOS 16.2. The reason were problems with some users. Instead of faster response times, devices responded slowly or were missing completely. In addition, no more users could be added to the home.
Meanwhile, Apple seems confident that these problems are under control. In the current beta of iOS 16.3, the upgrade is possible again. If there are no more major problems, the upgrade should be available to all users again with the release of iOS 16.3 in a few weeks.