What caused the iOS DCIM folder structure to change?

For years, whenever I connected an iOS device to my Windows computer, in file explorer I saw a DCIM folder with subfolders following a pattern of 100APPLE, 101APPLE, 102APPLE, etc. Today when connecting one of my devices (running iOS 14.6), I noticed those folders are gone. Instead, the pattern seems to be YYYY__MM (e.g. 2013__01 and 2021__07). However, on a second iOS device (running iOS 14.7), the folder pattern is unchanged--I still see the original folder names.

What triggers this change? Is there a way to switch back? At first I thought it was updating to iOS 14.6; since my second device has an even more recent version, though, I'm wondering if there's some other necessary condition to trigger the folder name change.

I've found a couple references to this around the internet, but nothing definitive.

Solution 1:

After I upgraded my first device to iOS 14.7, the subfolder pattern switched back to 100APPLE, 101APPLE, 102APPLE, etc. This makes me think the date-based folder structure was something specifically done (or perhaps accidentally exposed to users) in iOS 14.6.