Parameters passed into QUrlQuery cannot be reliably retrieved in a QWebEnginePage using URLSearchParams

The current combination of QUrl/QWebEnginePage/QUrlQuery cannot be used to create a pipeline where all parameters added to a QUrlQuery can be retrieved inside the webpage with their original keys and values.

I've included a qmake project to demonstrate this.

It starts with a QList of QString pairs. Then adds them to a QUrlQuery, which is added to a QUrl which loads a page. The code in the page uses the Javascript URLSearchParams API to retrieve the parameters.

It repeats this for a total of 4 combinations of encoding the QUrl and the QUrlQuery. The appears to be no combination in which the original QList<QPair<QString,QString>> can be retrieved from Javascript.