Our brain most strongly remembers novel experiences. If you've done the same thing over and over again it all kind of blends together, but something new sticks out. This is also why time seems to pass more quickly as you get older, you're having less novel experiences.

Watching the invasion realtime is something none of us have experienced before and was really stressful for most people. It was also smack in the middle of a time where most people had really boring day-to-day lives due to pandemic restrictions, so it REALLY sticks out.