Made Deepslate tunnels the Nether.  Bottom is slabs.  Surrounded by nettherack on the outside.  I experienced kinetic energy trying to fly through the tunnels.  Immediately returned from respawn at the world generation point.  All of the items I was wearing (helmets, elytra, pants and boots), plus the rockets I was holding were gone.  The rest of the items in my backpack were waiting for me to pick up.  The version I am playing just says 1.21.44, so I don’t know if “Hotfix” is right or not.  It was the only option given.