The red one is actually using a fixed joint to keep it in the bucket unless its knocked really hard. Are you playing on the Quest 2 version of the PC version? The PC version is every so slightly different as I added 3 colliders at the bottom of the well to keep the key from falling too close to the edge and away from the player. The Quest2 version I couldn't be assed to compile the build again with those changes so there is a chance on that version the key falls a little bit through the mesh so you can't see it anymore.
We decided to purposely let the player stand up and cheat a little, we figured they could probably still stand up a little bit anyway if their legs and hands were bound but not their waist.
I've since updated the game on my end but I'm going to add a few more bells and whistles and update that version after the jam ends. Thanks for playing!