Laravel date before_equal is allowing all dates through

 $DOB = $request->input('DOB');
 $allowed = Carbon::now()->subYears(26)->format('Y-m-d');

 $validatedData = $request->validate(
    ['DOB' => 'required|date|before_or_equal:'.$allowed],
  );

  <input type="date" name="DOB" class="form-control" required>

I am having a hard time validating dates in Laravel.

If I enter 01/01/2018 in the form, the validation does not catch it. Below it what is returned if I dd() the variables.

dd([$DOB, $allowed]);

array:2 [▼
 0 => "2018-01-01"
 1 => "1992-04-26"
]

No idea where I am going wrong.

via Chebli Mohamed