This might be a simple, I've `$month` and `$year`, but I'm trying to get `lastMonthYear` and `lastToLastMonthYear`.

```
    $date = Carbon::create($year, $month)->startOfMonth();

    $sameMonthLastYear = $date->subYear()->format('Ym');
    $lastMonthYear =  $date->subMonth()->format('Ym');
    $LastToLastMonthYear = $date->subMonth()->format('Ym');

```

Considering $month=9 and $year=2021, I'm trying to get

```
sameMonthLastYear = 202009
lastMonthYear = 202108
lastToLastMonthYear = 202107

```

but I'm getting

```
sameMonthLastYear = 202009
lastMonthYear = 202008
lastToLastMonthYear = 202008

```

Because $date value is keep updating for every line. Is there any way to get the expected result?