If you decide to sign off a realm on top of a chest or ender chest (like I commonly do), when signing back in the character glitches its lower portion into the chest block. If its a double chest, you can walk through both blocks until exiting them in which you cannot phase through them again until you repeat the process.
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We're tracking this issue in MCPE-84023, so this ticket is being resolved and linked as a duplicate.
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