DSCOVR is a pretty cool project. It always stays on the sunlit side of the earth and has a decent camera (called EPIC) viewing the full disc. You can view it here[0].
I have two thoughts.
1. it would be near the tonga volcano
2. it is suspiciously right in the middle of the image. Sun glare due to the orbit matching the sun?
edit: added link to image in question as I realized the earth actually spins.
[0] https://epic.gsfc.nasa.gov/