A little while ago, I tried using the following link to downgrade my HomeKit architecture: https://appldnld.apple.com/iOSProfiles/HomeKitReset.mobileconfig
it unfortunately does not work and, to this day, gives me a “Not Found on Accelerator” error. If anyone could please reupload the profile, I’d be more than grateful! Thank you!
iPad Air
I would imagine that ship has well and truly sailed. While Apple may have supported downgrading for a short time when this upgrade was first introduced doesn't imply they were going to continue to do so. This post from 2023 probably gives the clearest indication that this was a temporary measure - Downgrading HomeKit back to old architect… - Apple Community:
Profile Installation Failed
The profile "Home reset configuration and keep legacy Home architecture" is no longer valid.
In other words it probably stopped working long before the download was removed, and even if you could download the profile and attempt to install it, it isn't going to do anything useful.
tt2
Apple HomeKit: Architecture Downgrade is Broken
