This has been happening since 1.16.1 on my Nintendo switch but experienced this glitch on my friends Xbox 1. I will sometimes randomly clip through blocks (normally those blocks are above the player) occasionally I can walk through walls but never fell through the floor. This issue only effects a small area at a time (like 3-5 blocks) so never a full chunk. The bug will stop after reloading the world from the menu. This is not because of the large 100 megabyte file size as this happened on my friends Xbox 1 on a world with only a 1 megabyte file size. I’m pretty sure this started on 1.16.1 but never pre 1.16. I am on the latest version of Minecraft bedrock (pocket edition etc.)