Unlike HFS+ backups, those on APFS volumes look different depending on how you try to access them. What you see in the Finder is an illusion not available to other apps.
snapshot
Analysis of the phases of backing up to APFS shows the many similarities with that to HFS+. Crucial differences arise from the use of snapshots as backups.
A blow-by-blow account of what happens when Time Machine in Big Sur performs an automated backup to an APFS volume.
How each of the three different backup schemes used by Time Machine has worked, and how snapshots can work as backups.
What tells me that macOS isn’t about to be swallowed up into iOS? Look at what’s happened with Time Machine in Big Sur, which has undergone as much development as it did prior to release in 2007.
How Time Machine has changed since it appeared in 2007, and how backing up to APFS volumes is different now it’s available in Big Sur.
macOS updates sometimes don’t work out right. What can you do to revert to the previous release? Did I hear you mention snapshots?
Have you checked how much free space is on your startup volume after the last update? Do you wonder where it has all gone?
Disk structure diagrammed for comparison, from the partition table, to HFS+ and APFS volumes, with further references.
What you need to know about the APFS file system, its containers and volumes, so you can understand errors and how to repair them.
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