After adding the polylines to the map, sometime it shows up with wired phenomena. Just like the line has been deformed and rotated. While zooming the map, the lines are shaking.
I recorded a video:
https://drive.google.com/file/d/14mY16pv7f2glIc9OIuFVSG7DthGX4Kr9/view
I don't know where it goes wrong because most of the time, the result is OK. I do add the lines on the main thread.