When you say that the user is “logged in but with the wrong credentials” I have to assume you mean “the user is logged in with correct credentials but does not have the permissions needed to access the page”. If users were able to log in with the wrong credentials you site would be badly broken.
That redirect, all by itself, won’t cause the error you describe. You can prove that by pasting the following into your theme’s header.php:
wp_redirect(wp_login_url( get_permalink() ));
exit;
Any attempt to get to a front end page will redirect but there is no infinite redirect loop. The problem must be where you have placed that code and you don’t include that information. I expect you have it somewhere– a hook maybe– that loads for the login page as well so that when the redirect gets started it never stops (until the browser gives up). Sorting that out will probably solve the issue at hand.
I have to wonder why you are using a user meta field instead of a capability, though. I don’t see why the built in permissions system can’t handle this.