Why is this libraries-override configuration not working?

Core has an example: https://git.drupalcode.org/project/drupal/-/blob/11.x/core/themes/claro/...

So, the library name to override is user/drupal.user and you need to specify the correct sub-path to the file. At a glance your first example looks correct.

Thank you for the direction. I will try again.

After doing more reading on overriding libraries, it turns out what I was trying to do can only be done from a theme info.yml file, and not from a custom module. To override a library from a custom module one has to use hook_library_info_alter.

I have resolved my issue and all is working after implementing the hook_library_info_alter.

Below is what I ended up doing.

function somemodulename_library_info_alter(array &$libraries, $extension) {

if (isset($libraries['drupal.user']['js']) && $extension === 'user'){
unset($libraries['drupal.user']['js']['user.js']);

$libraries['drupal.user']['js']['/' . Drupal::service('extension.list.module')->getPath('replacewith odule name') . '/js/replacewithfilename.js'] = [];

}

Thank you for assisting me with this.