In the case where you need to redirect some domain to the primary domain, you shouldn't do this by adding a domain alias to the primary domain in order to prevent negative consequences.
Those negative consequences could be:
1. You will insert too much unnecessary code into .htaccess
2. There could appear problems with renewing Let's Encrypt SSL certificates. The reason for this is if one of alias domains fail to update certificate, all others would also fail, including primary domain.
Additionally, here you can find how to properly redirect one domain to another: viewtopic.php?f=19&t=609