This very annoying bug finally got me killed. It seems to only happen once I get Elytra, but it continues to happen afterwards whether I have it equipped or not. What happens is my head will start passing through solid blocks. The rest of me body usually won't, so the result is my head can get stuck inside a block which starts killing me, like sleeping in a bed with a too short roof. This killed me in an End City, constantly getting hit by shulkers and levitating up to get my head stuck in blocks over and over faster than I could break them. I've seen others complain about this on reddit, but I couldn't find anything about it here when I did a search. Please add this to your next bug fix patch!