Weird. No love on my iPad mini 5th gen.
Anyway, all I can say is ShutterSnitch uses the system framework to load the photo and if it fails it falls back on the embedded JPEG. So if you're getting the embedded JPEG, the system didn't supply a parsed raw.
And I can rule out it being a bug in my app since it works on the M1. I get flashbacks to the original CR3 format which also caused a lot of
extreme weirdness. I wonder if we're in for another ride here.
Hah, just as I write this, I tried simply connecting my iPad to the Mac with a USB cable to see if some parser-info got transferred in the background, I go back to my Photos app - and boom it shows the photo. No more gray box. But I can't zoom more than the JPEG sized preview.
Then I go back to ShutterSnitch and whatta-ya-know: it parses the raw file. And can zoom to the full size. I did have to two-finger-double-tap the photo to have ShutterSnitch refresh the file info first though. (Keep an eye on the top right-hand corner - it'll flash the current position once it's refreshed the info.)
A good way to check if it really does parse the raw and isn't just fetching the embedded JPEG: In filmstrip mode, tap and hold the photo in the filmstrip and select "File information". If it's the embedded preview you won't get any info on the Details page. If it's parsed you will.