HEIC to JPG auto-conversion from iPhone not working

I want to continue to take HEIC format pictures on my iPhone, and copy them to my Windows 11 PC with automatic conversion to JPG. In the past this has not been an issue.

Online advice explains how to turn off the HEIC format on the iPhone (which I don't want to do), or how to select the correct setting for the automatic transfer. - That's what I want.

On navigating in the iPhone settings to "Photos/Transfer to Mac or PC" I am supposed to select the 'Automatic' setting. - Fine, but it's already selected!

.... So, what is it 'automatically' doing? The explanation below, says that this option is to "Automatically transfer photos and videos in a compatible format". From this description, I infer that my iPhone is now asking my PC if it can read HEIC, the PC says 'Yes', and the iPhone doesn't bother with the automatic translation, even though I've selected the 'Automatic' option.

If that's the case, how can I make the PC say 'No'? I tried deleting my file association for the .HEIC format, but this makes no difference. The file still copies over in HEIC, and the file association only affects whether I can open it immediately, or not.

So I have the impression that Apple want to make it look as if it is easy to achieve automatic file conversion on copying files across, while actually making it more difficult and promoting their own format.

Is there a way to alter the settings so that the automatic conversion still takes place, as it has been doing for me, until the last week or so? - Yes I am aware that the web is awash with apps and ideas that can do a file conversion between the formats. I'd like it still to happen automatically.