Forge of Fury - arrows on map

I took a peek through the forums, didn't see anything regarding this topic. I am not sure what the arrows on the GM Overlay is for. They kinda make sense for the direction of travel in Mountain Door, but not sure if that's still the case in Glitterhame, specifically around area's 15 and 25. I have the PDF for Yawning Portal, and the arrows don't exist there. Anyone have any input before my party gets down there?

I think the arrows indicate the "up" direction for stairs (or slopes).

could it be Difficult Terrain? one of the WoTC map sets has that per similar question before

The arrows show in DnDBeyond. I think they are for the “up” direction of the stairs. The “cliff” between 23 and 24 supports this theory (look at the corresponding stairs...)

That makes perfect sense and I'm ashamed to not have thought of that. Thank you all for your wisdom.