Return camera roll photos converted to HEIC back to JPEG

Apple Support spent more than an hour with me yesterday (case 102150306676) but couldn't figure out why iCloud backup shows as using 3G for Backup when it should be 0. Hopefully someone in their backend team can manually free up the iCloud space.

Since my above post I did a bit more digging on the JPEG to HEIC photo conversion and in addition to the possibility I alluded to above (Apple software trying to save space automatically by forcing the conversion) it is also possible that all the photos were HEIC on my iPhone since 2018, but were automatically converted to JPEG on copy to Windows so I never noticed. On my iPhone, Photos -> 'Transfer to MAC or PC' setting still shows 'Automatic', so for this possibility either an Apple update (17.1) or one of the following Windows updates - KB5032190 or KB5030509, would have caused the automatic HEIC to JPEG conversion to stop. Have asked the Microsoft community (Any HEIC format support changes ... - Microsoft Community) but no response yet. These Windows updates were installed the same day on my PC that the iCloud storage bloat issue happened and until a day before photos were getting copied over from my iPhone to PC as JPEG.

Anyway, for those wanting to convert HEIC to JPEG in batch, per my research so far it seems the best way is to use 'Shortcut's as outlined in

How To Convert HEIC to JPG [Simple Way] - Tech Junkie

For the benefit of Windows users who notice this issue with HEIC photos, I confirmed that Windows update KB5032190 is causing this behavior change. So HEIC photos on iPhone, with Photos transfer setting set to Automatic (as opposed to keep Original), will now show up as HEIC. Before this Windows update, HEIC photos showed as JPEG when browsing through File Explorer and were copied as JPEG. Now they show as HEIC and are copied as HEIC.

I verified this by connecting the SAME iPhone on two Surface Pro's - both running Windows 11 Pro - one with all the latest updates and one without. The one which didn't have KB5032190 followed the old behavior (HEIC photos treated as JPEG). The one with KB5032190 followed the new behavior (HEIC photos treated as HEIC). I then went ahead and installed KB5032190 on the one which didn't have it, and its behavior changed after the install - so now it too is showing HEIC photos as HEIC. Microsoft for some reason forgot to put in a sentence about this big change in their KB article for the update.

Seems the iCloud bloat issue (3G used by a non-existent backup, that is still unresolved for me) happened to just coincide with this Windows change.