People keep saying this, but it was nowhere near to the same extent as the backlash against Game of Thrones. Some people had an issue with Breaking Bad but it was mostly a minority, the majority were very pleased with the ending and the final seasons, the opposite is true of Game of Thrones. The consensus is pretty much (from critics and viewers) that S8 was a rushed and poor ending, so it's not really the same as a small number of people raising issues with the finale of Breaking Bad, which most people enjoyed.
Basically the entirety of S8 was not well received at all, and that will haunt how the show is viewed going forward. People will still see it as great television for the most part, but when you get a disappointing climax then the legacy will suffer.