Dortmund and Bayern Munich will always compete with each other, although this is a distinct advantage for Dortmund compared to Bayern Munich, who are burdened with continuing to maintain consistency at the top of the standings. But it needs to be seen so far that Bayern Munich strength is slightly above Dortmund. As you said, if Bayern slips a little and makes a mistake or lets one match go to waste, then that's where Dortmund will replace his position.
In terms of quality, I'm still optimistic that Munich is superior. but indeed Munich has been a little off guard this season by starting the season not so well and finally now they are back on a good trend. despite having the same points at the moment, it does not mean that Dortmund will get the title this season. there are still quite a lot of games left, and that makes the competition even more interesting. whoever is more consistent, they will deserve to be on top till the end. even Union Berlin haven't completely lost their chance for a trophy either.
Can Dortmund overcome the defending champion?
I see Dortmund are really challenging Bayern, After the 23rd round of the weekend, Bayern still holds the top of the table. However, they cannot create a significant difference from Dortmund, the two teams still have the same 49 points, and Bayern is only ranked above thanks to the difference. Dortmund is a worthy team to compete with Bayern this season, Leipzig or Union Berlin are showing signs of "exhaustion".