Languages Select not working for pt-BR livechat text

[Anderson-Vasques]

When changing Language to 'Português do Brasil' in admin/General the livechat You i18n text (https://github.com/RocketChat/Rocket.Chat/blob/0.74.0/packages/rocketchat-livechat/.app/client/views/message.html#L7) changes to 'Tu' (which is the text from Português translate)
I think the problem is https://github.com/RocketChat/Rocket.Chat/blob/0.74.0/packages/rocketchat-ui-admin/client/admin.js#L99 that changes pt-BR to pt-br. If I change the option value from pt-br to pt-BR on the option value, the correct text is displayed

Rocketchat version: 0.74.0

[Anderson-Vasques]

Removing toLowerCase from map could fix this problem, but I am not sure why toLowerCase was inserted.

languages() {
  const languages = TAPi18n.getLanguages();

  const result = Object.entries(languages)
    .map(([key, language]) => ({ ...language, key: key }))
    .sort((a, b) => a.key - b.key);

  result.unshift({
    name: 'Default',
    en: 'Default',
    key: '',
  });

  return result;
},
isAppLanguage(key) {
  const languageKey = RocketChat.settings.get('Language');
  return typeof languageKey === 'string' && languageKey.toLowerCase() === key.toLowerCase();
}