Chartjs-Chart.js positive/negative values fill with out twist

You are defining fill as true which is equivalent to origin for backwards compatibility. This mode fills to the zero line.

To get the behaviour you want you need to change from fill: true to fill: 'start'.

Here in the documentation you can see how all the different filling modes affect the chart: https://www.chartjs.org/docs/master/samples/area/line-boundaries.html