unless it has an IP rating in the specs then you have to presume it is not waterproof, that is why its not advisable to fly in fog or rain with out some form of protection fitted ,more expensive drones will have an IP43 rating, but that does not make them completely waterproof ,its the electronics that are most at risk and the battery from water ingress
Based on DJI's recommendations to keep it away from water, sand, dust, rain, snow, fog, and clouds, I'd say that it sadly does not have any dustproofness or waterproofness to speak of; however, I found this video of someone flying in pretty heavy rain. When it starts raining, I always land immediately to keep my drone safe & dry, but I'm not afraid of it getting a drop or two on approach to the landing zone after watching that video. I do recommend drying off the propellers and body if you have a 'wet landing,' to prevent any ice or frost in winter.
The fact that there are some youtube videos showing the drone flying in rain does not mean that the drone is splash proof. To be splash proof there must be some seals for stopping water to contact the electronics and electrical contacts but there is none.