Early in the video of the launch of the first sixty SpaceX Starlink satellites we can see that after stage separation the first stage grid fins open.
Around that time there are some phenomena I don't recognize after about
- bright flash of light
- blue "plasma clouds" (I don't know what it is really)
- bright white glow of the grid fins, fading to dark.
This was a launch in darkness and I don't think that sunlight was at play here. It seems to be a color camera of some kind (the blue stuff) so the grid fin glow isn't thermal IR, it seems to be white light.
What's going on? What causes these three phenomena?
(sorry for the low quality GIF, I used ImageJ because Giphy won't accept long YouTube videos.