Armor Stand's position is set when leaving the game with an open fence gate inside

Description:

If an armor stand has an open fence gate on its lower half, it will set its position to its “Hero” position. If this is intentional, it is very obscure, because it does not change position if any other block pushed into its bottom half and even if you push an open fence gate on its upper half.

Steps to replicate:

Create any type of world (superflat, natural, creative, survival, etc.).

Place down an armor stand with a block behind it. Any block works, solid or not.

Use a piston to push any type of fence gate into its lower hitbox (the bottom block of the armor stand).

Open the fence gate (This is the important part).

Leave the game and join the world again.

Notice the armor stand in in its ‘Hero' pose, and no matter how much you change it, as long as you leave and rejoin, it will always be set back to its 'Hero’ pose.

Expected:

The armor stand’s position to remain the same no matter how many times the world is rejoined.

Result:

The armor stands position is the 'Hero' pose upon rejoining the world.