Currently, https://donate.wikimedia.org/wiki/Special:LandingCheck returns an error:
No pages were found while performing the request.
This should not happen. I'm marking this bug as critical, as many pages redirect to this page from https://wikimediafoundation.org/wiki/Special:LandingCheck, including URLs such as https://wikimediafoundation.org/wiki/Fundraising.
First reported at https://meta.wikimedia.org/w/index.php?title=Foundation_wiki_feedback&oldid=4360044#Broken_donate_link_on_error_page by Topbanana.