Ok after reading my post a second time, i realize the steps to reproduce are unclear:
1. Have the map open on for instance a space platform, while being on a planet yourself.
2. ALT+D to start the deconstruction cursor.
3. Start dragging a rectangle.
4. Close the map.
5. Release mouse button.
6 ...

Hey,

I noticed that when i use the deconstruction planner on a platform and then close the map while dragging and then releasing on my main planet map, it marked pretty much everything for deconstruction. My base was practically destoying itself haha.

Im not sure if you can call this a bug, but i ...