I looked in the HTML source and guess what - they use the Highcharts, which looks customizable.
<svg version="1.1" class="highcharts-root" style="font-family:"Lucida Grande","Lucida Sans Unicode", Arial, Helvetica, sans-serif;font-size:12px;cursor:crosshair;" xmlns="http://www.w3.org/2000/svg" width="1860" height="400" viewBox="0 0 1860 400"> <desc>Created with Highcharts 6.1.4</desc>
They don't use the newest version 8.0.0 (2019-12-10), they use 6.1.4 (2018-09-25), but it was still quite customizable.
For sure they could at least set the max and min parameters to cut not matching data.