Looking at the statistics of the match, I think it was a match where Borussia Dortmund should be happy with the 1 point they got. They had a very tough match and Bayer Leverkusen wore them out a lot. They are unlucky not to beat because they created a lot of chances. At least they were not defeated, so we have to think like that. Bayern will be the happiest with this loss.
This is not the first match in which Dortmund has acted in this way against a strong opponent, they did something similar in the match against Newcastle. For Dortmund, an away draw is a completely acceptable result, but for Bayer it is a loss of very important points, now Bayern will almost certainly be able to take advantage of these and get ahead of them, although if they win they will be equal on points, but Bayern will have a better goal difference.
At least they didn't lose this match, because if I look at the course of the match I can say that Leverkusen deserves to be able to win this match. They lost everything in this game, but they were lucky enough to score an early goal in the 5th minute, although in the end they had to defend to withstand Leverkusen's atacks. In the frst half they did a good job, but it's like that, no matter how strong they defend, if they continue to be attacked, it will create an opening too and that happened in the 79th minute when Leverkusen could create a goal to equalize the score.