Robert Lewandowski netted the game's winner in the 77th-minute from the penalty spot, but there are many who believe the Pole shouldn't have been handed the chance to score from 12 yards.
Dortmund defender Mats Hummels was adjudged to have handled the ball in the area from a Bayern corner.
Not a single player appealed at the time, but the incident was reviewed on the VAR monitor by referee Felix Zwayer and he deemed it worthy of a penalty.
Was Hummels' handball worthy of a penalty?
It looked an incredibly harsh call by the official and Dortmund's teenage sensation Jude Bellingham has made his feelings on the matter very clear.
In fact, the former Birmingham City midfielder gave one of the most savage post-match interviews of 2021, calling out Zwayer and referencing his match-fixing past.
Video: Bellingham's interview after Dortmund 2-3 Bayern
The England international said: "For me, it wasn't a penalty. You give a referee that has, you know, match fixed before, the biggest game in Germany, what do you expect?"
Wow. That interview may land Bellingham in a spot of bother with the German footballing authorities.
Erling Braut Haaland was also far from happy with the referee after the match, the scorer of Dortmund's second goal telling reporters: “I think it was a scandal when it comes to the referee. He [the referee] was arrogant and I will not say more.”
Video: Haaland's interview after Dortmund 2-3 Bayern
Now, you're probably wondering; was Zwayer really convicted of match-fixing? Well, back in 2005, he was banned for six months for his involvement in a German match-fixing scandal and for accepting a €300 bribe from fellow referee Robert Hoyzer, per Wikipedia.
Bellingham wasn't lying...