QString::normalized does not work as expected on some characters

// 03D2 0301;    03D2     # ϓ → ϒ    GREEK UPSILON WITH HOOK SYMBOL, COMBINING ACUTE ACCENT → GREEK UPSILON WITH HOOK SYMBOL
    //expected:ϒ, actual result is \u03a5  Υ
    QString a("\u03D2\u0301");//ϓ
    if(a.normalized(QString::NormalizationForm_KD).at(0).unicode()!=0x03D2){
        qDebug()<<"seems not correct";
    }
    //01B6;    007A      # ƶ → z    LATIN SMALL LETTER Z WITH STROKE → LATIN SMALL LETTER Z
    QString a1("\u01B6");
    if(a1.normalized(QString::NormalizationForm_KD).at(0).unicode()!=0x007A){
        qDebug()<<"seems not correct";
    }
//    correct example
    //1E7D;    0076      # ṽ → v    LATIN SMALL LETTER V WITH TILDE → LATIN SMALL LETTER V
    QString a2("\u1E7D");
//    qDebug()<<a2.normalized(QString::NormalizationForm_KD).at(0);
    if(a2.normalized(QString::NormalizationForm_KD).at(0).unicode()==0x0076){
        qDebug()<<"seems  correct";
    }