Most code was written in the time PHP 5.6 was the standard, so most is still compatible with that version. We will always support the versions that are still being supported on php.net. Currently that is 7.4, 8.0 and 8.1. We support older versions of PHP, but with new code being written we will use PHP 7 as a minimum, but doesn’t mean it will not work on older versions. I would suggest that when you update your code you also make sure to update PHP to a recent version.