Well they really shoved the drama in this chapter, to the point that it's even stated out loud by old mangaka, "sorry for making you feel awkward with all this sudden drama!"
I think the argument is pretty dumb, if she resented her for doing manga for fun then I would get it, I don't see how she "messed" with her though by complimenting her manga and helping out selling it. The whole exchange with her being like lol you sweet summer child just felt really odd to me
I just wanted her to be super gay for her as a hardcore Yuri fan/old mangaka, none of this sad childhood backstory angst