File Downloads via UI appear as .zip files

Downloading files from a project within the GitLab UI in Microsoft Edge/IE results files being downloaded as .zip files despite the files having a different file type i.e a .pptx file in a repository is stored as a .zip file. The file functions correctly as expected if the extension on the downloaded file is corrected.

I managed to reproduce this in Internet Explorer via Browserstack but I couldn't reproduce it in Chrome and Firefox on macOS. A customer working in a Windows environment experienced this behavior in IE, Microsoft Edge and Firefox v65.0.1 but not in Chrome.

Reproduction Steps;

Add a pdf,pptx,jpg,png or docx file to a GitLab repository. After an upload, navigate to the file in the GitLab UI and download the file in IE/Microsoft

Customer ticket: https://gitlab.zendesk.com/agent/tickets/115204