I'm too lazy to write everything out.
Demo Video https://youtu.be/1V_BbIvVznA
TL:DR: When you walk between a trapdoor on the ground that's in a raised position and a slab, and then proceed to close the trapdoor under you, your character model moves to a standing position but your hitbox and viewbox stay in a crouched position.
Environment
HP Pavilion 8GB 2400 DDR4 memory, Intel Graphics 620, Core I5 clocked at 1.6 GHz
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We're tracking this issue in MC-157183, so this ticket is being resolved and linked as a duplicate.
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