HasanMerkit looking at the code, it looks like the number of whole years between the birthday and now must be strictly greater than the setting value.
So in current version you would have to set 12
as the setting. The setting is more like "up to which age should an error be returned". I'm assuming this was not the intended behavior.
It seems like there's also a hard-coded 100 years old limit, which might end up causing issues one day too 😇 👴