[ureech]

var item = [];
   var arr = [];
   var res = '';

for (let key in obj) {
    a = obj[key];
    arr = a.split(',');
    res = [arr[0],+arr[1]];
   item[key] = res;
  }

На выходе

Array(9) [ (2) […], (2) […], (2) […], (2) […], (2) […], (2) […], (2) […], (2) […], (2) […] ]
​
0: Array [ "2021-10-04", 45 ]
​
1: Array [ "2021-10-06", 45.5 ]
​
2: Array [ "2021-10-20", 40 ]
​
3: Array [ "2021-10-31", 45 ]
​
4: Array [ "2021-11-01", 45.5 ]
​
5: Array [ "2021-11-03", 40 ]
​
6: Array [ "2021-11-10", 45.5 ]
​
7: Array [ "2021-11-16", 50 ]
​
8: Array [ "2021-11-26", 45 ]
​
length: 9

График ругается,если подставляю

var data = google.visualization.arrayToDataTable([
item
        ]);

Data column(s) for axis #0 cannot be of type string×