It is good for Leipzig though. Because they have been doing really bad in the Bundesliga for a few weeks. They are falling behind in the title competition day by day.
Just like you, I also expected the opposite result because Eintracht Frankfurt is considered more worthy to advance to the next round than RB Leipzig considering their good performance in the Bundesliga. But that's the reality, they lost and no one could predict what might happen in that match. I was a bit surprised that Marmoush couldn't even score a single goal for Frankfurt in this match.