Thank you for your reply. And your hint with the login_redirect filter solved my problem in a way that I can still update your plugin. So thank you again.
But I have to disagree with your assumption that registration doesn’t have redirects. Let’s assume you have some kind of website that allows more kinds of interactions…like reviews. So when the visitor wants to create a review, he will get to the login/registration page..and when he now registers, he lands on the homepage instead of the review form.