User login POST redirects to FormBuilder's placeholder form action

Problem/Motivation

User attempts to login at user/login and is redirected to /user/form_action_p_pvdeGsVG5zNF_XLGPTvYSKCf43t8qZYSwcfZl2uzM without being logged in. Receives "The requested page could not be found." message.

Steps to reproduce

If the big pipe module is installed, this problem occurs, reference is made to the FormBuilder's placeholder.

When you try to log in and it fails, Drupal creates an SSESS cookie, if this cookie is present in the browser, when you try to log in you will be redirected to the page not found.

Proposed resolution

When the module is uninstalled the problem no longer occurs.