I can’t really tell from the picture, but from the looks of it there is a large solder pad with four smaller pads beside it. It’s possible that it is a voltage regulator or other similar IC that has a large ground pad (for a heatsink) and four smaller pins. All of the pads probably have solder on them, but the large pad is the most obvious.

There are all sorts of reasons why a manufacturer would leafe space for a part, and then not use it. It’s possible that regulator is providing power to a part that is also not populated , or that the part that it powers has been redesigned to not need that separate power rail anymore. Designing a board like that is expensive, so if some parts are no longer necessary, they will just remove them from the build, and save actually taking the part off the board for the point in the future when they need to redesign it.