Hey all,
I’ve explored a lot and found this secret area in East march. Ofc, it’s already known but it’s empty.
Anyone knows what it is for?
Spoiler tags welcomed 
Probably created long ago by someone who decided against using it as a secret spot and simply forgot about it.
If we are talking about the place where the five-pointed star is, I am pretty sure there is a Hidden Spoils chest the first time you get there and a normal one on subsequent visits. Maybe revist the place and turn the cam a bit.
Huh what do you know, there is a hidden spoils there. 2.5k hours in the game and still I don’t know everything. Heh.
After Crate revised Old Arkovia shortly before the release in 2016, it took me over 1 1/2 years to stumble into a new secret area there. 
I checked again. Indeed, there’s a chest hidden in the cliff. I never move the cam’ …
I don’t know if you’re talking about something in the lowest level, or the one where you have to go through the sides. There is a chest, very well hidden (I can provide a screenshot, not now, but eventually in 10 - 12 hours from now. When I first went there, I also thought it’s empty, but the almighty interaction button showed me the light. Hidden Trove.