[Решено] my site breaks is broken in all languages

Background of the issue:
I am not trying to do anything specific. Suddenly, some pages in all my languages are broken. Here is a link to a page where the issue can be seen: скрытая ссылка

Symptoms:
My site is broken in all languages. Some pages are not displaying correctly.

Questions:
Why are some pages broken in all languages?
How can I fix the broken pages?