I'm totally baffled.
It seems to be an extremely bright reflection that persists at very low sun angles, then fades very rapidly at sunset, like a mirrored surface at a very high altitude above the surrounding terrain. I can't think of any natural model that accounts for that behavior. A snow-capped peak seems to be the only explanation, but somehow, that doesn't make sense on an airless rock. Ceres has no weather.
A volcanic eruption in the central peak would not suddenly fade out going into shadow, and surely Ceres is too small and cold to have any lava-type activity anyway. I can't think of any geological event or feature that would look like that.
This might be something truly wonderful.