If you have yellow and are targeted by yellow(yellow is an example, can be any colour) you dont die. you basically shield yourself.
I died to IX in phase 2 by getting a purple color deletion protocol (I had the purple bisector buff), so at least this week, you do die if you get your own color. It was hard mode IX and it was the only time that it happened. It ended up not affecting us too much. We raised me back up and still finished the fight fine, but it does seem to be a messy bug.