Tldr
Blackpink even from their debut era having more akgaes compare to the other groups. Jennie was always expected to be the popular one and the pushed member because she had that rep as "YGs princess" since predebut. Then Lisa as the first female idols from SEA that get into the big company already get support from Thailand and SEA fans. Lisa and Jennie stans against each other immediately and that kinda led the way for the fans of the other two girls as well. People hated that Jisoo seemed to get shafted and then people started talking about Rose getting mistreated and the fandom never really recovered. I think it was almost inevitable from the start that Blinks were going to be torn as a fandom moreso than groups normally are, at least that's how it seemed to me when Boombayah came out.
Therefore, even the smallest matter will be a debate and akgaes are very fond of exaggerating the situation. At each comeback, akgaes for each member attacked the other members to the point that their Instagram comments were full of insults from the solo stan. If you notice, if Bp is involved in a scandal, the harsh one mostly coming from the solo stan of their own group. For example when Jennie's lazy scandal and Lisa's durag scandal.
There are also solo stan that boycott their albums and only want to spend money on their faves individual activities. Logically, Yg themselves benefit more from the girls individual activities. Rosé and Lisa's mini album outsold bp except their full album. Yg personally see that bp is more profitable individually than in groups because they have 4 main money makers rather than one with Bp as the group.