Environment：
1.Ubuntu20.04.
2.Qt5.15.5
Demo:knobs.zip
Operating Steps：knobs
1. Both display screens are touch-enabled.
2.Run the demo for the PopupWidget in the attachment on the main screen
3. Touch and hold the circle in the demo without releasing, then disable touch functionality on the other screen via command line（echo 0 > /sys/bus/usb/devices/usb3/3-1/3-1.2/authorized）.
4. Release your finger from the circle.

As shown in the log from kncks_longtouch_issue.png, the current touchPoint.id is 0.
This causes all Qt widgets to become unusable.

Qt-related source code and logs：qxcbconnection_xi2.cpp and qxcbconnection_xi2.cpp_log.png
Set the environment variable QT_LOGGING_RULES to qt.qpa.input=true for logging：touchPointID.png