I watched some of the nasa livestream since I don’t have eyewear in a ~96% area, and it’s total overcast anyway. They basically said it’s a CME (or flare?) edit: “solar prominence”, and not surprising due to the sun being near the most active phase of its 11-year cycle.

Pretty cool that one made such a clear appearance. If you search for solar flare, you’ll see images of that similar arch visible in the photo. Must have been amazing to see one with the naked eye.