Coming from an anonymous user in a 4chan thread is a low res image of... some
kind of grey prototype style movie Optimus Prime. The timing is close enough to potentially be a prototype of an item from the first wave of the regular The Last Knight
toyline, if we assume a launch date in May, giving rise to the notion this could be a Leader Class version of Optimus Prime. But there's also a range of other likely possibilities as well based on examination of the image. You can click through to learn more and see the image to judge for yourself.
The nature of the image is such that it appears to be a photo taken of an image displayed on a screen. This would hardly be the first time someone leaked out an advance image using this method. Indeed, the first look at a sample of Titans Return Blaster happened in a very similar way.
While a Leader Class figure is one possible thing this might be, it's also possible this is some other sort of merchandise. The near-complete absence of vehicle parts visible on the body could suggest some sort of non-transforming, poseable figure. Other details give cause to question as well. The majority of the item in the picture is in prototype grey, but the head seems to be in full color. Also the hands are an unusual sculpted style and on the level of detail we can see right now, do not look like they're made for 5mm type accessories. Each of these factors could point to something outside the standard toyline.
Another possibility might be that this is a genuine prototype - an image of a one-off hand-crafted or 3D printed piece made to work out physical details and engineering concepts. The color head might be borrowed from an existing Optimus Prime toy, in that case. If this were the truth, then it might also help to explain why there's little or no vehicle discernible: those parts may simply not be added to this stage of presentation.
Of course the final answer is the one that should always be considered with unsourced images: It's a fake. That's probably not the likely outcome of this, given a majority of these kinds of images we see turn out to be genuine, but it always needs to be kept in mind that fakes do happen. Whatever the case may be, we'll continue watching this for further developments, so keep checking back with us for the latest!