Highcharts x-range datetime not shwoing with “Date.UTC(2023, 6, 20)”

I am using Highcharts x-range to show data in date range.
the graph is not showing with quotes "" for startdate (x) and enddate(x2).

"x": "Date.UTC(2018, 8, 18)",
"x2": "Date.UTC(2023, 6, 20)",

Sample Code added in JS fiddle https://jsfiddle.net/w1b6atc8/

no luck with Date.parse.