Apart from naming conventions there aren't any specific conflicts between the Moodle Code styling (MCS) and PSR for class declarations. 

PSR doesn’t mention magic methods MCS does

MCS: https://moodledev.io/general/development/policies/codingstyle#functions-and-methods-1 

PSR: https://www.php-fig.org/psr/psr-12/#44-methods-and-functions