As of November 25, I am unable to download student files using Safari. I have tested this at work and at home. It is isolated to Safari in both environments. Chrome does work ok. When Safari tried to download the file it hangs, then only downloads as a .html file
Please note, this is a new issue, on Monday Nov 23 I was still able to download successfully from Safari.
I see that you have been using Safari versions 13 and 14, which are supported. When I googled it, I saw that some users have had trouble with a cross site tracking feature in Safari that when turned off allows Safari to download files from Canvas. Did that help?