Vertical scrollbar issue with QtWebEngine + macOS + Apple Magic Mouse

[Fabrice Zuma]

We have frequent issues (macOS only) with the vertical scroll bar on QWebEngineView.
When the "Show scroll bar" preference is set to "Automatically
based ..." in macOS preferences and when we use Apple Magic Mouse,
sometimes the scroll bar disappears permanently. This is true on all
QWebEngineView embedded in our application. This is more common with the
latest Magic Mouse but it happens every day with our customers who use Magic
Mouse. What can we do for them, knowing that we don't want (we can't)
configure macOS preferences with "Show scroll bar" set to
"always".
Thank you