Part of the charm of the hugely-popular "No Man's Sky" is that its first of its kind procedurally-generated universe is open for all its players to explore. That means there are so many things out there (animals, plants, locations, entire planets even) that can be discovered—that even the game's developers aren't even aware of—which the players can name.
However, there seems to be something bugging the "No Man's Sky" servers. Players have been logging on to find out that the discoveries they made have disappeared from the game.
According to the "No Man's Sky" subreddit, some players have been backtracking to locations and planets they've already visited and seeing that although the name of the planet and star system had remained, the locations, flora, and fauna the players named had been erased. When a planet reverts to pre-discovery state, everything that can be named will go back to being called "?????", perhaps leaving them open to be discovered by other players in the game.
Another "No Man's Sky" player, Ultrasilvanus, verified that this was indeed happening to some discoveries. What's more is that it looks like the game is systematically deleting older discoveries first as the game's lifespan goes on.
This isn't the first time this has happened, however, as there were already reports of overridden names popping up soon after the game released. Players who subsequently travel to these planets will apparently get to rename anything you can find in these areas, which takes away from the fun of being a space explorer—considering there's a nearly-infinite number of systems you can travel to within the game.
GameSpot has tried to contact "No Man's Sky" creator Hello Games and publisher/financier Sony to get their comments on this issue, but they haven't made any statements yet. Hello Games is hard at work at releasing new patches for the game, which still has a number of issues post-launch. The developer needs to work on fixing these bugs as well as providing a better play experience, as the reviewers have noted that the game's premise ends up being bland and monotonous after a while.