Like you said there's plenty of teleports that arent in OSRS to get to places super easy, and if they were able to get there via teleport they should know how to get back, plus this is one of the very few item sinks we have in this server, unlike OSRS that has a huge player base and Jagex buying items back from players via the G.E. item sink, this would only make it more impossible for items to be removed from the game. The only thing I'd like to happen is if you die when a instance closes the items would be put outside the room, but even then it gives players some self accountability to be mindful of how much time is left and focusing on not dying or just restarting an instance for this exact reason.
TLDR; self accountability is better than making it almost impossible for players to lose items in the game.
I've also noticed the Runelite plugins Aren't in sync with games timers for certain boosters such as vote books and especially Drop boosters. Could be a Runelite issue specifically in regards to what I'm talking about.
+1 Support this triggers my ADHD not perfectly utilising boosters/vote books without time waste and the timers being out of sync as-well aha.
definitely out of sync, here's a screenshot of what I'm looking at currently, I enlarged the bonus xp timer on the side to make it easier to read.