Another idea, if the door has taken waterdamage it might got crooked a bit, all of a sudden not letting you through anymore.

Did a teammate modify the terrain in front of the door? If they did you can dig down in front of the door with a pick, put a stair in the hole, and flatten the terrain (a tiny bit of the stairs has to protrude from the ground) and that tiny bump should allow you to get in an out again. (You might have to jump if you didn't get the stairs just right).

Regular doors are indeed just tall enough to walk through. If you don't fit, you probably put a horizontal wood beam either on top of the door, or at the footstep.

Not sure why IG did that, but it led me to mostly using the larger gates as doors.

Use gates , normal "doors" are like garden doors to me lol ( and i use them in my farms lol )