> tried to convert it by renaming the HEIC file to PNG. Changing a file’s extension does not guarantee that it will be converted, but Spencer was still able to submit the demo test with no problem.
This should really say that changing a file's extension will (almost) never mean that the file is converted.
Anyway, it seems like today's students have missed out on the arcane knowledge of renaming a jpg/mp3/whatever to .docx, submitting it, pretending that it got mysteriously corrupted, and getting an extension until whenever the professor realizes the issue. (I've never done it, but I've heard legend.)