IKR, the new path which Kpop is following has just been releasing noise to appeal to westerners. Of course the digital performance would drop so dramatically. Groups is general are performing WAY worse than 2016 per say.
I know its the chosen path for bgs (they get a ifandom willing to support them), but honestly many ggs started doing the same loud/rap heavy/full of english songs that koreans aren't into, so it's understandable why old releases are gaining popularity, only OMG from recent years have tried to appeal to korea's public, that's the reason their results are great now. I feel like even some big ggs are catering more to ifans's taste, it shows on how their Spotify numbers grew but their melon rankings are lower