Not quite. As long as there is enough coolant in the reservoir to cover the hose, when the engine is cool, you are okay .... but, you should refill the reservoir. You should check this often as it does evaporate. Always try to maintain the reservoir level at the full mark with the engine is cold. The reservoir capacity above that mark to the cap is for expansion (not the area between low and full).Just because it is below the low line doesn't mean there is a problem. When the engine is cold the level should be at the low line and rise to the full line when at operating temp.
I have a 2018 and I have the same issue! It’s at 22k miles right now and I’m noticing it more since I moved back to WA with it. Especially after driving for long periods of time and idling. Really only on the passenger side. But today I smelled it through the vents after idling for 20 minutes after a long drive. I take it in every 6 months and got recalls fixed. Getting the brake recall fixed next week so will ask them then. Haven’t checked the coolant level when the engine is cold yet like some recommend.I have a 2019 with 4900 miles on it now and I too notice the coolant smell. I inspected the engine compartment very carefully and can find no signs of a leak. It is definitley antifreeze that I smell. It is most concentrated under the hood on the passenger side. It doesn't matter if I am running the heater or not, windows up or down, occasionally I smell antifreeze. It is a sick sweet smell. Yuck. So far my reservoir is full. A friend told me this is normal for Subaru's (really???).
If this is normal and not something to worry about (as so many people online seem to smell antifreeze and still run their cars to 100,000 miles with no problems), my interest is actually finding out where the smell is coming from? Curiosity is killing me!