The language switcher is unable to point to the correct kb article from one non-default locale (or more precisely URL with non-en slug) to another locale, incl. even back to en/default.
Preconditions
Arrive at a kb page in a non-default locale that you perhaps don't understand, and intend to switch to another locale you can read. (Technically: the page has to be translated, to have non-en-default page title, and also not in a language that doesn't put the localised/UTF slug in the URL, so e.g. a Korean would be an exception to this issue.)
Describe the bug
The language switcher is unable to point to the correct kb article from one non-default locale (or more precisely URL with non-en slug) to another locale, incl. even back to en/default.
Preconditions
Arrive at a kb page in a non-default locale that you perhaps don't understand, and intend to switch to another locale you can read. (Technically: the page has to be translated, to have non-en-default page title, and also not in a language that doesn't put the localised/UTF slug in the URL, so e.g. a Korean would be an exception to this issue.)
Steps to reproduce
This only works when switching away from eg. Korean https://support.mozilla.org/ko/kb/tabs-organize-websites-single-window, because that has the default slug in URL preserved and can be navigated to any other language without any error.
Expected behavior
Being able to switch arbitrarily, e.g. from https://support.mozilla.org/da/kb/saadan-indstiller-du-din-startside to https://support.mozilla.org/nl/kb/De%20startpagina%20instellen
Actual behavior
The switch ends up not found https://support.mozilla.org/nl/kb/saadan-indstiller-du-din-startside (Dutch locale with Dansk slug)
Desktop (please complete the following information):