Steps to replicate the issue (include links if applicable):

• Open https://diff.wikimedia.org
• Сhange the site language several times

What happens?:

The next time you try to change the language, the transition will not occur. When this happens is not clear (sometimes the transitions do not work completely), but more often when choosing English and some language later. Unfortunately, I was able to clearly determine when the error occurs

What should have happened instead?:

The transition to any language should proceed correctly

Software version (on Special:Version page; skip for WMF-hosted wikis like Wikipedia):
Used various devices, browsers and geolocations, but could not determine any dependency

Other information :
Trying to change the URL manually is not successful. Noticed something strange: the English version of the site and English posts, unlike the others, does not use the language code in the URL; https://diff.wikimedia.org/en redirects not to the English version, but for unknown reasons to the Spanish article. (?)