ageism is literally acknowledging the cultural and societal expectations that create judgment against certain age groups. it is not a statement of fact, it is a statement of contemporary norms that actively hurt whatever group you're referring to. there is not a single "factual" facet of what you just said. people don't turn to dust when they hit 30.

there is no reason kpop groups have to "expire" at any point because their age is no factor in that. if a group is unable to remain fresh/innovative/interesting, then that is when they "expire". to correlate that to age is to be ageist.

secondly, irene being, in your idea, "expired goods", is a pretty nasty slap in the face to anyone over 30 in the industry rn thats killing it, or trying.