Tinymce: Remaining URL of links gets corrupted after publish

Description

Within the tinyMCE editor, if you add a Remaining URL on a link that contains special characters, it gets corrupted after publish.

Example: before publish "?test%20check=1". After publish "?test%2Bcheck=1"
%20 has been changed to %2B

Steps to reproduce
1. In a tinymce editor, create a link to an internal page and append the following as the Remaining Url: ?page=D S.
2. Publish changes and check how the link is rendered on UI => the Remaining Url should render as ?page=D+S.
3. Open the link in tinymce again and add a title to it.
4. Publish again.
5. Check how the link is rendered in the UI.

Expected
The Remaining Url should render as ?page=D+S

Actual
The Remaining Url renders as ?page=D%2bS