Dortmund's performance this season should have been a little better as they are playing in the semi-finals of the Champions League this season and they have a chance to qualify for the Champions League final if they beat PSG in the first leg of the semi-finals. However, this team has performed badly in this season's league tournament due to which they did not qualify for the Champions League next season and they will qualify for the Europa League next season. They needed to improve their performance enough to qualify for the Champions League again next season.
Yeah actually Borussia Dortmund should have increased their performance this season because is very bad for them after going this far on the champions League and they could not qualify for the next season champions league, however it was really unfortunate for them because they started peaking form when the season had already gone far if not they would have at least managed to qualify on the champions League next season.
Although they may still have a chance to qualify because they have a close points with RB Leipzig, although their points different is 5 points but the only way for them is only if RB Leipzig will lose up to two matches from their remaining one that's the only way Borussia Dortmund could qualify but I doubt if that would be possible because RB Leipzig targets is also on the champions League next season so they will never entertain any mistake.