There seems to be a double scaling of TimeLineBar.Height in TAdvSmoothTimeLine.GetTimeLineRect and TAdvSmoothTimeLine.GetTimeLineBarRect.
The relevant code in both methods looks like this:
DPIScale := GetDPIScale(Self, Canvas); cHM := Round(DPIScale * HorizontalMargin); cVM := Round(DPIScale * VerticalMargin); cH := Round(DPIScale * TimeLineBar.Height);
It is just that TimeLineBar.Height is already adjusted to the current DPI. Thus the following calculations are done with a double scaled Height value.