step property
To show only every n'th label on the axis, set the step to n. Setting the step to 2 shows every other label.
By default, when 0, the step is calculated automatically to avoid overlap. To prevent this, set it to 1. This usually only happens on a category axis, and is often a sign that you have chosen the wrong axis type.
Read more at Axis docs => What axis should I use?
API Docs: https://api.highcharts.com/highcharts/chart.parallelAxes.labels.step
Implementation
double? step;