claiming "the southern raiders is a zvtara episode" is e n t i r e l y different than someone saying "the southern raiders is an episode that has a partial concentration on katara's relationship with zuko." these concepts are distinct (and only the latter is canon) and therefore they should not be conflated. yet they still are. that is where people trip up.
tsr was, first and foremost, an episode about katara, with a secondary concentration specifically on her relationship with zuko (e.g. her anger and her process to forgive him). but it was not a "zvtara" episode in terms of any canon romantic coding. the difference is simple. furthermore, tsr allows plenty of room for fanon expansion in a multitude of directions, and yet you still see the fandom getting up in arms about it.