My collected notes on WordPress.
If a WordPress plugin calls the same function, or filter, as you do in your functions.php, the results can be unexpected, even causing your site to be disabled.
Although the child theme’s functions.php is loaded by WordPress right before the parent theme’s functions.php, it does not override it. The child theme’s functions.php can be used to augment or replace the parent theme’s functions. Similarly, functions.php is loaded after any plugin files have loaded.