When doing the update to MacOS 11 or when reinstalling MacOS after MacOS after 10.13, or 10.14, when first connecting an iPhone to the updated computer MacOS will request to do an update to its system, via a window in the middle of the screen to update the interfacing to the iPhone. This also means you are unable to recover individual files from earlier Time Machine backups after installing 11.7. and the only way to access them is through Migration Assistant unless you have another bootable drive with an earlier version of Big Sur. The bottom line of all of this is that MacOS 11.7 changes in Time Machine format results in all Time Machine backups by earlier versions being inaccessible. I then verified it was a 11.7 issue by rebooting my machine using a different drive formatted with 11.6 and the Time Machine backups were accessible by it. This was verified with an Apple Support Agent screen sharing and seems to be something that Apple Support was unaware of. After hours of effort, I was able to access the backups via Migration Assistant and was able to recover my data. In fact, the App indicate I had no backups.

After the reinstall, I attempted to use Time Machine to recover my data and found out that Time Machine could not access any of my Time Machine backups under 11.6 and earlier as it could not recognize the format.

In my efforts to erase and reinstall the System, a Big Sur install reformatted my drive without warning resulting in the complete loss of all user accounts on the drive. After installing the Big Sur Security Update 11.7, resulting in corruption of the code that updates the Mac for iPhones, I went through procedures to reinstall Big Sur by rebooting using System Recovery.

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