HEIC isn't simple, and isn't common.
Apple should convert to JPG or PNG when exporting the image to anywhere anytime.
The same problem happens with webp images too - totally unusable almost everywhere, even in photoshop.
Apple wants to reduce storage space photos take up. Fine - but they should convert back to a standard format when exporting the image to be used on some other system.
With that said, it seems the issue is from students that didn't upload the image from their phone (where Apple correctly converts to JPG), but rather transferred the image to their computer, then uploaded into the AP Exam.
If that's true, then this is absolutely on Apple. Why would they export in a format that literally nobody else supports. What are these people supposed to do with a folder full of HEIC formatted photos, that can't be uploaded anywhere else, edited with any program, or opened even opened on some Operating Systems?
Apple should assume nobody else uses HEIC because... well, nobody else uses HEIC.