Flutter slider always show value indicator, double show

I want to display the value indicator always. Even user release the slider
Unfortunately it seems not to be implemented out of the box in flutter.
So according what I read it has to implemented with custom painter.
The problem is, I have now double of indicator when user tap slider.

My painter:

class _ThumbShape extends RoundSliderThumbShape {
  final _indicatorShape = const PaddleSliderValueIndicatorShape();

  const _ThumbShape();

  @override
  void paint(PaintingContext context, Offset center,
      {required Animation<double> activationAnimation,
      required Animation<double> enableAnimation,
      required bool isDiscrete,
      required TextPainter labelPainter,
      required RenderBox parentBox,
      required SliderThemeData sliderTheme,
      required ui.TextDirection textDirection,
      required double value,
      required double textScaleFactor,
      required Size sizeWithOverflow}) {
    super.paint(      context,     center,      activationAnimation: activationAnimation,      enableAnimation: enableAnimation,      sliderTheme: sliderTheme,      value: value,      textScaleFactor: textScaleFactor,      sizeWithOverflow: sizeWithOverflow,      isDiscrete: isDiscrete,      labelPainter: labelPainter,      parentBox: parentBox,      textDirection: textDirection,    );
    _indicatorShape.paint(
      context,
      center,
      activationAnimation: const AlwaysStoppedAnimation(1),
      enableAnimation: const AlwaysStoppedAnimation(1),
      labelPainter: labelPainter,
      parentBox: parentBox,
      sliderTheme: sliderTheme,
      value: value,
      textScaleFactor: 1,
      sizeWithOverflow: sizeWithOverflow,
      isDiscrete: isDiscrete,
      textDirection: textDirection,
    );
  }
}

My Slider call:

SliderTheme(
                  data: SliderTheme.of(context).copyWith(
                    thumbShape: _ThumbShape()
                  ),
                  child: Slider(
                    thumbColor: changed
                        ? Get.theme.colors.purple
                        : Get.theme.colors.grey,

                    // activeColor: changed ? Get.theme.colors.purple : Get.theme.colors.grey,
                    value: _currentValue,
                    min: _minValue,
                    max: _maxValue,
                    label: calcString(_currentValue),

                    divisions: _maxValue.toInt() - _minValue.toInt(),
                    onChanged: _updateValue,
                  ))

When slider is untouched it shown as follow (Good):

When user tap slider is shown as follow (Bad):