November 9th, 2022
That means that any modifications to that object modify or mutate the original value.
1$start_date = new Carbon('2022-01-01');2$end_date = $start_date->addMonth();3 4dd($start_date) // 2022-02-01 just like $end_date, $start_date was mutated in the process5dd($end_date) // 2022-02-01We can change the Carbon Object to Immutable, so it doesn't change original value. That can be done with: Carbon clone date or new CarbonImmutable
Before addMonth clone Carbon date, so that initial value of carbon date doesn't change
1$start_date = new Carbon('2022-01-01');2$end_date = $start_date->clone()->addMonth();3 4dd($start_date) // 2022-01-015dd($end_date) // 2022-02-01Create CarbonImmutable date instead of just Carbon date, which doesn't change its value after addMonth
1$start_date = new CarbonImmutable('2022-01-01');2$end_date = $start_date->addMonth();3 4dd($start_date) // 2022-01-015dd($end_date) // 2022-02-01