Created attachment 120718 [details]
Screenshot

SUMMARY
Placeholder text for the username is not consistent to actual requirements

STEPS TO REPRODUCE
1. Open the User Manager

OBSERVED RESULT
Username field's placeholder is inconsistent

EXPECTED RESULT
It should start with a lowercase letter

SOFTWARE/OS VERSIONS
Linux: 5.1.7-arch1-1-ARCH
KDE Plasma Version: 5.15.90
KDE Frameworks Version: 5.58.0
Qt Version: 5.13.0

ADDITIONAL INFORMATION
The first letter must specifically be lowercase.
This might be relevant (from user-manager source; src/accountinfo.cpp):
QString AccountInfo::cleanUsername(QString username)
{
    if (username.isEmpty()) {
        return username;
    }

    if (username[0].isUpper()) {
        username[0] = username[0].toLower();
    }

    username.remove(QLatin1Char(' '));
    m_info->username->setText(username);
    return username;
}