What the spinning symbol is doing
A game does not preserve every moment of play automatically just because it is running. It must turn the current state—such as your position, inventory, and completed objectives—into save data and write that data to storage. The spinning icon is a signal that this transfer is still underway, not merely a reminder that a save is due.
Why power matters during a save
Storage writes take time. Until the game has finished, the newest progress may exist only partly on the device. If power is cut mid-write, the game may lose that recent progress; in some cases, an incomplete save can also be difficult to load. The exact risk depends on how the game and device handle saving, but the icon marks a moment when the process has not yet confirmed completion.
That is why a brief wait matters when shutting down a console or unplugging a device. Letting the symbol disappear gives the game a chance to finish writing and close out the save cleanly. A few seconds of patience can be the difference between resuming at the latest checkpoint and having to replay what came after it.
