Some Qt5 ui file does not compile with Qt6

Strangely some Qt5 ui file which compiles good with Qt5, does not compiles with Qt6. For some reason ui.xxx.h file tries to connect with slot in parent class instead of derived class.

Attached ui file example can be used to reproduce it:

1: download unzip and qmake make using Qt5 qmake

It compiles without problem.

2: download unzip and qmake make using Qt6.2.1 qmake

it gives following error:

uic/ui_guicoorddlg.h:141:94: error: no member named 'formDone' in 'QDialog'
QObject::connect(buttonOk, &QPushButton;::clicked, guicoorddlg, qOverload<>(&QDialog;::formDone));