Links to media files on other WordPress sites getting changed

I’m trying to add links to other WordPress sites on one of my multisites, but whenever I do WordPress automatically adds “/site/{my-site-ID}” to the urls. For example I want to link this url on page: https://humanrights.alaska.gov/wp-content/uploads/2019/09/sexual-harassment-poster.pdf
and when I add the link it saves correctly in the admin, but on the page itself it shows as https://humanrights.alaska.gov/sites/{my-site-id}/wp-content/uploads/2019/09/sexual-harassment-poster.pdf and I get a 404 error when opening the link

Is there any way to prevent this from happening?