Background of the issue:
Suddenly, my client reported that one of our translations (EN) returns "Page not found" at every page instead of it's content. In admin, content is show but cannot be saved.
Symptoms: hidden link
Questions:
How to get the content back? hidden link ASAP
Updating the site to WordPress 6.6.1 version solved the trouble, but I thought that having 6.5.5 should cause this problem. All the debug info should be caught in the debug info or my screen share.