Keeping WordPress up to date is very important, but if you want to avoid a WordPress auto-update breaking your site, then you can simply add this block of code to your wp-config.php file. This code will stop WordPress auto-updating, if like me, you had problems with the latest WordPress 5.5 update, then you’ll be switching auto-update off. Of course, this means you’ll need to make sure you keep WordPress up to date with manual updates. This solution also works well if you’re on Siteground web hosting, which doesn’t let you turn auto-updates off.
define( 'WP_AUTO_UPDATE_CORE', false );