SOURCE

const data = [
    [1, 1, false],
    [1, 1, true],
    [1, 1, true],
    [1, 1, true],
    [1, 1, false],
    [1, 1, false],
    [1, 1, true],
    [1, 1, true],
    [1, 1, true],
]

const arr = [];
let i = 0;
let isContinueData = false;

data.forEach((item, index) => {
    if (index < data.length - 1 && item[2] === data[index + 1][2]) {
        if (isContinueData) {
            arr[i] = {
                ...arr[i],
                end: index
            }
        } else {
            arr[i] = {
                start: index,
                end: ''
            }
        }
        isContinueData = true
    } else {
        isContinueData = false
        arr[i] = {
            start: index,
            ...arr[i],
            end: index
        }
        i++;
    }

})

console.log(arr)