HomeKit suddenly started recording and notifying all "Motion Detected" events from cameras despite restricted settings

This has been reported before but there have never been any clear solutions. After working properly for over a year, HomeKit has suddenly started sending notifications from our security cameras whenever ANY motion is detected despite us choosing the proper settings to restrict the notifications. Here are the key configuration details:

• our Home Hubs consist of up to four HomePod Minis
• all of the cameras are Logitech brand -- one doorbell and two Circle View cameras (all purchased from Apple)
• "Activity Notifications" for every camera are set in the Home app to "Specific Motion is Detected" and then "People Are Detected"
• "Recording Options" for every camera are likewise set in the Home app to "Specific Motion is Detected" and then "People Are Detected"
• every camera has a very small and specific "Activity Zone" that sees little activity on a normal day

At some point on the morning of Friday, November 15, 2024, HomeKit started behaving as if none of the above settings mattered. The symptoms:

• we are constantly getting unwanted notifications from all of the cameras about "detected motion" (as well as the desired notifications about "detected a person")
• the timeline below each of the camera views in the Home app show a recording for ALL of notifications but they appear as black lines (no thumbnails) for the "detected motion" events, and correctly with thumbnails for the other proper "detected a person" events
• viewing the black-bar "detected motion" recordings show that the motion occurred OUTSIDE the defined Activity Zones
• the process started at first with just one camera (the doorbell) but evolved over the weekend to affect every camera

In other words, HomeKit has stopped honouring the restrictions for both notifications and recordings. Our only effective options are to disable notifications and/or recordings entirely. This makes the cameras essentially useless for our purpose.

We have tried all of the previously-suggested solutions posted here and elsewhere but nothing has worked:

• rebooting all of the HomePod minis
• rebooting all of the cameras
• ensuring all of the involved devices are running the latest software (where possible*)
• toggling the various notification and recording settings in the Home app off and then on again
• deleting and recreating the Activity Zones for each camera

I mention latest software "where possible" because some of our older Apple devices (one iMac and a couple of iPads) cannot be updated to current OS's. We also have no direct control over the Logitech firmware. However, Logitech has been reported by others as stating that motion detection is entirely a feature of HomeKit and cannot be resolved by them.