The sun was just underneath the horizon, and things that are higher up can still get illuminated that way. When a rocket launch takes place during that time, the exhaust plume and all the gasses can be illuminated that way, which makes for this cool sight.
It's called a twilight launch. Doesn't happen all that often, but it's a sight when it does.
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u/Bubsy7979 1h ago
Did the booster blow up? The couple SpaceX launches I’ve seen in SoCal never had that huge blue cloud during separation