You have two spaces test and test2.

You add pages to space test2 with umlauts in title like "Döner" or "Pöbel".

You go to the test space's page "Home" and EDIT.

You add a link to the page with target space '"test2" and the page "Döner".

While you are still in the EDIT mode and WYSIWYG view the link is shown with an emoticon in the middle of the text.

When you save this you have corrupted links to nowhere.