Hi there, here's a bug with falling blocks. They can be used to clip through any kind of door. (Iron included)

STEPS TO REPRODUCE

Stand near a door

Make sure there is a falling block entity above you

 Now keep moving toward the door

Make sure you keep hold of the move button while the falling block lands on you

If you've done this correctly, you should be able to walk straight through the Door.

Observed Results: the player walks through the door

Expected Results: the player will stay next to the door (and may get pushed out of the way)

Thank you, and have a good day.