Initial beta versions of iOS 16 and iPadOS 16 had noticeable change in Home app. iPad was not eligible to act as Home Hub anymore.
Apple made a comment that iPad could be used as Home hub for “current features” while undisclosed “new features”, probably won’t be supported.
As of now, it seems that these “new features” are related to Matter standard which HomeKit is adopting.
Developer:Beware of possible limitations, test remote HomeKit usage accordingly.
QA engineer:Beware of possible limitations, test remote HomeKit usage accordingly.
PM/DM:Beware of possible limitations, consider updating corresponding marketing materials accordingly.