The only difference between Moodle Coding Style (MCS) and PSR-12 (PSR-1) for PHP tags is that MCS states only long tags: <?php but PSR-1 allows either <?php ?> tags or the short-echo <?= ?>

Required decision: Keep the MCS for tags or allow short tags as defined in PSR-1

MCS: https://moodledev.io/general/development/policies/codingstyle#file-formatting 

PSR-1: https://www.php-fig.org/psr/psr-1/ 

PSR-12: https://www.php-fig.org/psr/psr-12/#22-files