Hello, @denys-lvov,
This seems to be your plugin issue, Could you please try the solution described in the official documentation of the Polylang here: https://polylang.pro/doc/i-activated-the-plugin-and-my-posts-are-not-displayed-anymore/ I hope this should resolve your issue and if not then please share your site WP Admin URL and Credentials with us under the private area of this topic so that we can have a look into it for you on your site and help you out.
Best Regards,
PThemes Team.