Hey, thanks so much for all the feedback! A couple people ran into the same issue with the vines, but that's because I didn't make it clear that the answer was in the cave (the stick runes showed the order that the vines needed to be pulled in). I assumed the player would see the eye on the cave and by the river and make a connection, but I only later realized that most people wouldn't do a 180 before moving down to the river (makes, sense, why would you?).
Originally, I was really confused when you mentioned a canyon, as I didn't remember putting one in, but then I realized that you broke the game haha. There was (spoilers) actually a switch you pull to create a doorway that was accessible from the ground (which you get a map to by climbing the tree). I definitely agree with the lamp suggestion; I used them to try to lead the player up the tree, but neglected them until the end. Looking at the project file, there is indeed a flying shrub. Whoops, thanks for the heads up.
Again thank you for the feedback, I'm always looking to improve!
(By the way, I really enjoyed Welcome to the Void, I even sent it to my brother to play. Gameplay felt very clean)