Big bang was korean national boy group so to speak so their impact is too strong and it was like a goodbye song.
but how do you explain taeyang's solo flopping (t he one after the one that did with Jimin) or winner's releases flopping. Mino's solo album didn't that well either and he did well in his first album and not to mention Ikon's bad digital performance before leaving YG. Akmu was already well known before joining YG though
Winner or ikon were never at the level they could be called digimons, they had a few hits yes but were never guaranteed chart toppers and that was before the burning sun scandal, other factors and chart changes didnt help them either, and just like most kpop groups with a few exceptions, most will lose public relevance within a few years naturally either way.
Like its just not YG boygroups doing bad, its every boygroup doing massively worse in the last few years (BTS excluded) on korean charts.
Taeyang have only ever had one #1 song solo in 2014, and vibe did better than his 2017 release which was before burning sun. With how the charts works today i dont find his followup song placement that surprising.
The only bigbang member that could be considered to be a proper digimon as solo is gd.
Im not really arguing that YG is doing much worse now than before burning sun, my argument is that they would likely not be doing much better now even if burning sun didnt happen. But then again if burning sun didnt happen, bigbang would still maybe be active and releasing music and help hold the ship up instead of it all hinging on blackpink for the last few years.