When was the last time IU had a comeback that seemed to lack much impact. Wonder how much less it would have been as well without special appearances in MVs and features.
There was the Pieces mini-album at the end of 2021 but it wasn't a proper comeback (no physical album, also at that point she was pretty saturated since "Strawberry Moon" was released just 2 months prior).
"Bbibbi" in 2018 also peaked only very briefly (iirc, a Zion.T release overtook it within a few days) and also had poor longevity (by IU standards) - ironically it was a lot more popular with ifans judging by its YT views and Spotify streams.
IU only releases albums every other year or less so it's hard to judge within small time frames but I'd say these are more lackluster comeback eras compared to her peaks (which have been Real, Last Fantasy, Palette, Love Poem, and Lilac):
- Modern Times (2013)
- Chatshire (2015)
- Bbibbi (2018)
- Pieces (2021)
IIRC no songs from Pieces achieved a CAK whereas at least the other eras all had at least 1 PAK but mostly the issue was lack of the typical IU longevity.