After installing WordPress 6.3, this site was broken because the new version of WordPress isn’t compatible with PHP 5.x.
I know WordPress has been complaining about this for a while, but PHP 5.x is the default version on CentOS 7, which is still supported until June 30, 2024.
I would expect that WordPress would, instead of encouraging the users on systems with old versions of PHP to apply the update, warn that applying the update will absolutely break the target website.
I’m exceedingly annoyed at WordPress. An absolutely terrible experience.
I currently have the site running on a temporary server that is a little fragile, it remains to be seen how stable it will be over the coming days.