I know this is an old post, but I'm playing through the game now, and I encountered the same thing, so for posterity's sake, here's the answer. It seems that when a player completes maps on other planets, they can spend 'Legacy' points to manipulate the terrain, which is shared by all players ala No Man's Sky. Apparently a number of players have been deliberately wiping the player's starting terrain as a form of griefing. Frankly, it ruins enjoyment of the game, since there's many maps that are like this. Maybe if you launch the game the first time on a computer with no Internet connection, and never connect while playing the game, you'll get the original, default maps.