It was Kuu's cover version of Sayonara no mukougawa they've performed.
Vocals were overall great, but I prefer the performance of We'll Be OK.
We'll Be OK is still doing decently on Line Music, around #35 daily.
For comparison - GOLDFINGER 2019 was weekly #1 on Line Music in 2019.
But streaming and Line Music grew exponentially since then, so a weekly #12 position is indeed as good or even better than that two years ago.
We'll Be OK already is her 66th most streamed track on Line Music, right after Eh Yo and surpassing puff soon, GOLDFINGER 2019 is her 74th most streamed track in total streams on there.