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Your form action point to the url in which the login form is displayed, and this is many times not the desired behavior when you write your own login form. You should let the login end point handle the login. The result should be something like

<form .... action="<?php echo esc_url( site_url( 'wp-login.php', 'login_post' ) )?> ">

Where site_url( 'wp-login.php', 'login_post') is the specific way to find the login end point.

Obviously when using plugins that mess around with the end point, you are at the mercy of the quality of the implementation.