Patreon users being able to log into your site via Patreon is expected behavior. That is in case you meant registration and log in by ‘accessing my site’. If any Patreon user is able to access content that is locked by a certain tier, then that’s a problem. If so, let me know. But unless you want to make your site’s registration and login for patrons only, you dont have any issue at this moment. If you want to do so, the pro upgrade to the plugin provides login locking by tier.