How to get fields name dynamically in row of element plus table?

In Laravel 12 / vuejs 33.5.13 / element-plus 2.9.5 app I have a table with dynamic columns in labels array like :

    <el-table :data="items" style="width: 100%"
              :row-class-name="tableRowClassName"
              :header-row-class-name="headerRowClassName"
    >
        <el-table-column label="ID" prop="id"></el-table-column>
        ...

<!--        create dynamic list of columns  -->
        <el-table-column v-for="(label, index) in labels" v-if="labels"
                         :key="label.title_field"
                         :prop="label.value_field"
                         label="Label Text"
                         :min-width="80">
        </el-table-column>


    </el-table>

I found branch Background colors to rows of a element-ui table with pagination in vueJS 2 but failing to render
and I to make in similar way but I do not know how can I refer to column name dynamically, as any row has columns like :

labels_length
item_1_value
item_2_value
item_3_value

and method :

methods: {

    tableRowClassName({row, rowIndex}) {
        for (let i=0;i< row.labels_length;i++) { //
            if(100 < parseInt(row.getFieldValueByName['item_'+i+'_value'])) {
                return 'warning-row-class';
            }
        }

The row var has no any method like getFieldValueByName and I wonder in which way I can get fields name dynamically ?