I'd expect the following code:

EJSON.parse('{"grant_date":{"$date":{"$numberLong":"1452124800000"}}}', {"relaxed": true}) 

To give me:

{ grant_date: 2016-01-07T00:00:00.000Z }

But I get the current time:

{ grant_date: 2018-04-30T17:10:14.832Z }

The Stitch JS SDK like to give users types back in a relaxed format after parse which normally works with the above for most types but it's not working for $date since a $numberLong becomes a "number" and the $date decoder cannot parse that.