[Решено] There has been a critical error on this site.

Background of the issue:
I am trying to switch the language on my blog page from the default language (English) to another language. The page in question is скрытая ссылка.

Symptoms:
There has been a critical error on the site when changing the language on the blog page. This issue is recent and did not occur before. The server error logs do not report anything, and all other aspects of the site and WPML work fine.

Questions:
Why is there a critical error when changing the language on the blog page?
What could have caused this recent issue?
How can I resolve the error when switching languages on the blog page?