Touchscreen press(down) events appear with a delay

Dear Qt team,
 
I discovered a touch input problem with QtQuick (qml) in Qt 5 and Qt 6 on Ubuntu. Press(down) events appear with a delay of ~170ms in Qt. The weird thing is, that release(up) and click events are working as expected. Only press(down) has this delay. To exclude a system/hardware problem I checked the logs from xinput, press events have no delay there.
 
The problem appears in PySide2, PySide6 and qmlscene (Qt 5 and Qt 6). I did not check older versions.
 
I used different types of Iiyama touch screens (e.g. IIYAMA PROLITE TF2415MC-B2).
 
How to reproduce the problem:

• Connect a touchscreen to your Ubuntu system (20.04.3 LTS)
• Download the online installer for Ubuntu and install Qt 6.2.0
• Install moreutils to add time stamps to xinput outputs:
  sudo apt install moreutils
• Create a qml file with (main.qml):

  import QtQuick 2.2
  import QtQuick.Window 2.2
  
  Window {
      title: "test"
      width: 800
      height: 600
      visible: true
  
      Rectangle {
          anchors.fill: parent
          color: "blue"
      }
  }
  

• Start the Qt application with qmlscene: QT_LOGGING_RULES="qt.quick.touch=true" QT_MESSAGE_PATTERN="%{time hh:mm:ss.zzzzzz}: %{message}" qmlscene main.qml
• Start xinput logging to proof the delay (check xinput list to get the ID of your touch device):
  xinput test 10 | ts '%H:%M:%.S'
• Press the blue Qt window
• Output qmlscene:

15:45:01.999999: QQuickDeliveryAgent(root=QQuickRootItem) QTouchEvent(TouchBegin device: "eGalax Inc. eGalaxTouch EXC3188-4623-09.00.00.00" states: Pressed, 1 points: QList(QEventPoint(id=133 ts=93229220 pos=461.982,384.642 scn=461.982,384.642 gbl=1169.98,658.642 Pressed vel=0,0 press=461.982,384.642 last=461.982,384.642 \u0394 0,0)))
15:45:04.004004: QQuickDeliveryAgent(root=QQuickRootItem) QTouchEvent(TouchEnd device: "eGalax Inc. eGalaxTouch EXC3188-4623-09.00.00.00" states: Released, 1 points: QList(QEventPoint(id=133 ts=93231399 pos=461.982,384.642 scn=461.982,384.642 gbl=1169.98,658.642 Released vel=0,0 press=461.982,384.642 last=461.982,384.642 \u0394 0,0)))

• Output xinput:

15:45:01.825381 motion a[0]=39935 a[1]=39967 
15:45:01.825792 button press   1 a[0]=39935 a[1]=39967
15:45:04.004288 motion a[0]=39935 a[1]=39967 
15:45:04.004419 button release 1 a[0]=39935 a[1]=39967 

 
You will see the delay of press events the terminal outputs
 
Please let me know if this problem could be solved.
 
Thank you.