The backdoor was removed before it was compiled into a binary for admins to download so there is no issue for anyone running PHP. However this does prove to be an issues in regards to PHP's safety - They have moved to GitHub (@girish mentions in his reply) and will be better closely monitoring pushes and merges into the code base.
PHP's Own Nikita Popov: "The changes were on the development branch for PHP 8.1, which is due to release at the end of the year" which means the code has not been distributed. It's a big deal but not as big as everyone is making it out to be.
Not an expert on minecraft. But it seems that multicraft uses php and you can adjust php.ini to have the correct timezone setting i.e edit /app/data/php.ini and set the data.timezone to one of the values in https://www.php.net/manual/en/timezones.php.