This may be related to https://tracker.moodle.org/browse/MDL-81313 and https://tracker.moodle.org/browse/MDL-81316

Issue: When adding a URL activity, slashes in any part of the URL after a question mark (IE query parameters) are encoded, other special characters are not. In my case this is breaking student proxy access to a library database.

To replicate:

Login to Moodle https://sandbox.moodledemo.net/

In a course, create URL activity and observe the link the user is directed to:

https://example.com/demo -> https://example.com/demo

https://example.com/demo?param1=string/with/slashes -> https://example.com/demo?param1=string%2Fwith%2Fslashes 

https://example.com/demo?param1=string/with/slashes&ersands-dashes -> https://example.com/demo?param1=string%2Fwith%2Fslashes&ersands-dashes