I know this is mean of me, but the student who was taking her Computer Science exam and who apparently thought that changing the file’s extension would change format? Yeah... she deserved to fail.
its not unheard that websites do only extension validation for uploads, worth a try!
That totally misses the point though, because if the website only validates on the basis of extension and accepts the format in an unrecognised format, the backend won’t know how to handle it anyway. There’s no point uploading a HEIC file disguised as a PNG (or whatever) if eventually somewhere along the workflow an examiner is actually going to have to open that file in a program that doesn’t know how to parse HEICs.