The driver incorrectly parses a single-digit hour for $date:

{"":{"$date":"0070-01-01T0:00:00Z"}}

It should error because ISO 8601 (and RFC-3339) require a two-digit hour.

This turns out to be a Go bug (#37616), but can be fixed by changing the parsing format string to 2006-01-02T03:04:05Z07:00 custom validation.