I have a similar issue but in the hedge maze. I died by a bunch of spiderlings and my backpack fell in the crease of two branches but the icon was showing it was inside the branch where the two branches connected. I ended up giving up since I could not retrieve it.
The latest update has my game lagging really bad where I see water drops dancing and not being able to pick up items or attacking doesnt show but later does or I die but 10 seconds later but Im on PC.
Did you go to leave feedback and click on Im stuck? It records your location and tells the devs so they can look at it to prevent any future stuckness.
In this particular area of the hedge, I was killed by spiderlings after using the first zipline. I chose send feedback ingame but both of my backpacks are stuck within the tree.
Oddly I have the game in both Steam (for PTS) and Game Pass, both run fine now with no crashes upon loading so thats why I think it might be on your side?
I would wait in two days there should be a new update. Have you tried verifying your files?? Maybe your HDD is corrupt or the game filies?? This happened to me but they fixed in last update. Have you uninstalled/reinstalled it? Are you on Game Pass or Steam???