Mitchel Broussard, writing for MacRumors:

As shown in the pictures shared today, the adapter’s cord appears short and visually similar to that of Apple’s current adapters sold on its website, including the USB-C to USB and Thunderbolt to Gigabit Ethernet accessories. The Lightning plug does not appear to fit particularly well into its sheath, but it’s unclear if it might be an incomplete part, damaged during disassembly, or simply a knockoff product.

The legitimacy of this particular adapter seems sketchy to me, but if Apple does release a product like this, I expect it will look very similar.