Calculate Age in months for inside a condition

I am attempting to calculate Age in months from the DoB - date of birth summited by a user. This computed age is used as part of conditions to qualify or disqualify a user.
The reference date is 2022-06-20. As the person should be 35 years or by 2022-6-20.
I have tried using the Dateiff function but seems I am doing something wrong because the form attached to the server action is still qualifying users less than 35 years.

For example, when the DoB is 1987-09-20 the condition should return false but I still get the dynamic event for success triggered.

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here is code view of Condition
$_POST.dob.dateDiff('months', '2022-06-20' >= 420)&&($_POST.age >= 35)&&($_POST.currentRank.contains('principal') && ($_POST.duration >= 4))