So I went back to my PC and Mac and it looks like this is actually an issue that only occurs on Safari. Up until a couple weeks ago I never had issue with that browser. Looks like there is a possible answer on stack exchange:
“AFAIK the Apache server software comes with a preset of extension->MIME-type assignments. If a file with an unknown extension (like .dmg) is served with the MIME-type text as a fallback, Safari adds a .txt extension. This behavior is arguably correct. The server tells Safari it is serving a text-file, and a text file needs a .txt extension on Mac to be opened with a text editor. So Safari adds one. Other browsers ignore the server, which is a short term benefit for the user, but in the long run a) makes the server admin not notice the mistake and b) prevents the server admin to use this feature whenever he intentionally wants to (as opposed to unintentionally doesn’t care as usually).”