I think it's a mix of reasons. Big groups are oversaturated, the pandemic boom meant people wanted to participate in community in some way and often had more free time, people that got into kpop dueing the pandemic moving on to other interests, the economic situation for most people globally is becoming more difficult, the way that people pass between girl groups when the new big thing happens, less fansigns since the pandemic boom so less reason for fans to bulk buy. I do think it's an ever-changing market though.
