New maps do not follow normal rules of expansion if another map has been made in the same area. The general rule is that when expanded, map will add more terrain away from the player. However, if there is another map in the world that has been expanded in a certain direction, future maps made and expanded in the same area will always mimic the existing map, regardless of where the player is standing. The linked video does a better job of explaining it
Linked issues
Comments 3
https://youtu.be/5JogJ0ugBVI?t=202
So basically if you have an expanded map and make a new one within the area the map covers, the new map will always expand to match the old map. The normal rule is that maps expand away from the player.
The normal rule is that maps expand away from the player.
No, it isn't. It used to be like that, but it is not like that anymore. Maps are based on a layered grid system. Quote from the Minecraft wiki:
Maps are always aligned to a grid at all zoom levels. That means zooming out any map in a specific area covered by that map will always have the same center, regardless of where the map was originally centered. As such maps will be aligned by map width (1024 blocks for a level 3 maps) minus 64. As such a level 3 map generated at spawn will cover X and Z coordinates from -64 to 960. All maps generated in this area will zoom out to the same coordinates, guaranteeing that they are always 'aligned' on a map wall.
It works like that since 14w31a (1.8). Maybe look into the comments of the linked bug report MC-64909 (where this was first reported) if you still don't understand how this works. See also MC-36639.
Duplicate of MC-64909, this is working like this since 4.5 years now. It is like this so you can create larger maps using item frames without needing to worry about alignment.
If I misunderstood your report please either link to the timestamp in the video on which this video is explained or (preferrably) explain this issue in detail in this ticket.