Why is my ridgeline plot not closing correctly?

I wanted to make a Ridgeline Plot, which changes, when using a dropdown menu to change the data.
Started with a simple attempt first, and first rows are fine, but one of them is kinda off.
The line is not closing on the same y-coord. like at the beginning of the line-path.path not closing in one of the rows of my plot

The code snippet:

const kde = kernelDensityEstimator(kernelEpanechnikov(7), xR.ticks(150)) 

  const allDensity = []
  for (i = 0; i < monthN; i++) {
      key = monthsAvg[i]
      density = kde( yearData.map(function(d){  return d[key]; }) )
      allDensity.push({key: key, density: density})
  }

  svgR.selectAll("areas")
    .data(allDensity)
    .join("path")
      .attr("transform", function(d){return(`translate(0, ${(yNameR(d.key)-heightR)})`)})
      .datum(function(d){return(d.density)})
      .attr("fill", "#69b3a2")
      .attr("stroke", "#000")
      .attr("stroke-width", 0.5)
      .attr("d",  d3.line()
          .curve(d3.curveBasis)
          .x(function(d) { return xR(d[0]); })
          .y(function(d) { return yR(d[1]); })
      );


  function kernelDensityEstimator(kernel, X) {
    return function(V) {
      return X.map(function(x) {
        return [x, d3.mean(V, function(v) { return kernel(x - v); })];
      });
    };
  }
  function kernelEpanechnikov(k) {
    return function(v) {
      return Math.abs(v /= k) <= 1 ? 0.75 * (1 - v * v) / k : 0;
    };}

When I change the y-coord. manually in the browser it will come out correctly. But since I have a function drawing the plots based on my data, I have no idea how to approach this issue.

If anyone has an idea how to make every plot end on the same y-coordinate, I would be really glad.