User's language preference is not applied!

Problem/motivation

Currently having an issue that when viewing a node that it ignores my user language preference and shows the language based on my second Interface text language detection method which is url.

This is being caused by an if statement in:
core/modules/user/src/Plugin/LanguageNegotiation/LanguageNegotiationUser.php

In the getLangcode function shown below, there is an if statement which has a check were the 'user' preferred_langcode needs to be different from the default_langcode.

  /**
   * {@inheritdoc}
   */
  public function getLangcode(Request $request = NULL) {
    $langcode = NULL;

    // User preference (only for authenticated users).
    if ($this->languageManager && $this->currentUser->isAuthenticated()) {
      $preferred_langcode = $this->currentUser->getPreferredLangcode();
      $default_langcode = $this->languageManager->getDefaultLanguage()->getId();
      $languages = $this->languageManager->getLanguages();
      if (!empty($preferred_langcode) && $preferred_langcode != $default_langcode && isset($languages[$preferred_langcode])) {
        $langcode = $preferred_langcode;
      }
    }

    // No language preference from the user.
    return $langcode;
  }

Steps to reproduce:

- Create at least two languages
- Set default language to English
- Go to user edit settings and set default language to English.
- In the admin/config/regional/language/detection settings. Set User as the first detection method and Url as second.
- Clear the cache
- Visit a node edit page with other language prefix, then your default language (English) in your url. e.g: nl/node/123/edit
- Interface language will display in Dutch (Which I would not expect).

Proposed solution

In my opinion the $preferred_langcode != $default_langcode check needs be removed. Because default langcode could be the same as preferred langcode and should not skip the Detection method if they are the same.