Qt QML MapRoute line is not very well constructed, flickering

I am trying to develop a navigation application with Qt and Qt location plugins. Right now, I am testing using Here plugin.
Since the Map plugin allows me to set up tilt, bearing, zoomLevel etc. I am well able to do what I am trying to do, except with a flaw in the line that is constructed by RouteModel and MapRoute that is viewed on the screen. The following is how I am able to display the route:

MapItemView {
    model: routeModel
    delegate: MapRoute {
        route: routeData}}
        line.color: "#d0021b"
        line.width: 7
        antialiasing: true
        smooth: true
    }
}
 

As I increase the zoom level and take a closer look at the route, I can see that the route flickers, and on some parts even not very well displayed.

An example of this situation is as follows:

I could see that the picture corrects itself and the flickering stops if I change zoomLevel from around 18 to 10. But this is not what I want since I want the navigation feel. I am looking for better ways to draw this route, simply.

I tried with both Qt 5.8.0 and Qt 5.10.1, with Here map plugin. Step to reproduce would be getting a route map from Dortmund,Germany to Izmir,Turkey, and zooming in with zoomLevel 18, 19 or 20 at Königswall street. (This flickering happens in many occasions, this is just one example to reproduce)

EDIT: Added details
map.center = QtPositioning.coordinate(51.516056, 7.455889)
map.tilt = 67
map.zoomLevel = 18
map.bearing = -135.32097597706982

I don't know how to solve this problem and I would appreciate if I could get some advice. Thanks in advance.