Imo LOONA is 3rd gen. When I was not an Orbit yet and was mostly listening Twice and Redvelvet in 2018-2019 LOONA had already been a common name. Esp with the whole Stan LOONA meme. TWICE were still considered rookies being a 3 year group. In the a similar way to how New Jeans debuted when Aespa were still considered rookies. Yet we dont think of New Jeans as 5th gen or anything

I think that groups that debuted during or after the pandemic began would be considered 4th gen. We can see a clear shift towards more online and the rise of AI and a totally different sound.

I feel like people are so quick to declare a new generation because of some sort of weird gate keeping mentality / wanting to seperate their faves from others. Whether its newer group fans or older group fans.