When you post in WordPress with over 5MB text post, you may receive this error with red color.
Publishing Failed
or you found in your php error log
PHP Fatal error: Maximum execution time of 60 seconds exceeded in /home/nginx/domains/juzhax.com/public/wp-includes/formatting.php on line 2295
This is because WordPress need more time to execute and process and formatting your post over the maximum execution time.
You may use the way below to solve this.
Edit the file wp-config.php and add in the line
@ini_set('max_execution_time', 1800);
But, use this with caution, because if many of your script in WordPress over this time, this way maybe kill your server.