Array reduce method is overwriting the first element

Question

below is my function which have reduce method

    getFilters(gridFilters, columnList){
      const filtersArray = [];
      let filterObject = {};
      gridFilters.forEach((ele, i, arr) => {
        filtersArray.push(...arr[i].filters);
      });      
      const _filArr = filtersArray.reduce((acc, {field, operator, value}) => {        
        filterObject['columnName'] = field;   
        filterObject['filterValue1'] = value;
        filterObject['filterOperator1'] = operator;
        filterObject['filterValue2'] = '';
        filterObject['filterOperator2'] = ''; 
        columnList.push(filterObject);    
        return acc;
      }, {});    
      return columnList;

Here, filtersArray will have 2 array elements like'

    Array(2)    
    0:
        field: "objectType"
        operator: "contains"
        value: "lic"
        [[Prototype]]: Object
    1:
        field: "attributeDisplayName"
        operator: "contains"
        value: "date"
        [[Prototype]]: Object
        length: 2
        [[Prototype]]: Array(0)

But after pushing the values to the columnList array, I am seeing the second object (which has attributeDisplayName) is coming for both values. Basically the first object (which has objectType) is getting overwritten with second object in array.

This is how the columnList is getting overwritten

    Array(2)    
    0:
        columnName: "attributeDisplayName"
        filterOperator1: "contains"
        filterOperator2: ""
        filterValue1: "date"
        filterValue2: ""
        [[Prototype]]: Object
    1:
        columnName: "attributeDisplayName"
        filterOperator1: "contains"
        filterOperator2: ""
        filterValue1: "date"
        filterValue2: ""
        [[Prototype]]: Object
        length: 2
        [[Prototype]]: Array(0)

Can some one please suggest what I am doing wrong here. Thanks