WordPress changes language code

I generated a share plugin for LinkedIn from this site: https://developer.linkedin.com/plugins/share, but when I tried to display on my page (in a text widget), it’s displayed in english, even though it’s coded to be displayed in danish (lang: da_DK).

When I tested the code on this site https://jsfiddle.net/ and it shows up in danish like it should, so that means it must be WordPress changing/ignoring the language code.

What’s going on, and how do I fix it?

[ No bumping please. ]