Which exact Vaadin version are you using? … I did a small test with the latest version (an application with login enabled created at start.vaadin.com) and just by adding the servlet.session.cookie.same-site=none property it works fine, no redirect loops.
Can you create an application on start.vaadin.com with security enabled and try it by yourself? … if it works maybe you could compare it with your application to see if you can spot a significant difference.
If you can reproduce the problem with a sample app, I can take a look.