There are probably a few reasons why people from Bavaria are a bit disliked, like for example: heavy dialect, (low key) separatist tendencies, it's the bastion of Christian conservative right wing politics in Germany, stupid Americans confusing Bavarian traditions with Germany. Now with Bayern fans it's kind of obvious I guess: Bayern wins too often, for the longest time their two main guys were entitled hypocrites and literal criminals and of course the glory hunter fans.
Hate is a strong word, but generally speaking Dortmund have profiled themselves as the keepers of football values, so there's some form of tension with fans of plastic clubs, who represent the ideological opposite. With Watzke lobbying to cut their share of TV money over their lack of fans. As far as I'm aware Gladbach fans usually have a strong dislike against Dortmund mainly over mainly buying Reus, Hazard and Rose, but also Dahoud and indirectly Favre. If you somehow come across a Leverkusen fan in the wild they can also be feisty, again, because of the buying angle (I think it really stung when Dortmund bought Gonzalo Castro, but also Toprak and Brandt) and of course the whole (defund) plastic angle and the older ones probably remember when Leverkusen shat their pants in 2002 and Dortmund snatched the title from them. And I'm sure that by now Dortmund, too, have picked up a few glory hunter fans, who annoy neutrals. But I think in general Dortmund haven't won enough to be universally disliked and still profit from not being Bayern (or Leipzig).
that's what we're here for at the end f the day.