The KPop act which debuted the latest to chart in Hot 100 is Illit.
In other words, no acts since Illit gained enough traction to be charted in Hot 100.
The following KPop acts charted in Hot 100. (Individual activities are not noted separately. People who sneaked in there by featuring with a BTS / BlackPink member, like Cho Youjeen, Loco and Park Hyoshin, are not counted separately.)
In order of debut
Pinkfong (a children's show in Korea - its signal music rose all the way to #32 in Hot 100 and actually made the annual chart)
BTS
Twice
BlackPink
Fifty Fifty (if Ablume ever charts it won't be counted separately)
Illit
Fin.
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No boy acts since Stray Kids, debuting in 2017.
And out of the 4 girl groups debuting after Stray Kids, only Le Sserafim has any hope of charting again. It will be very, very unlikely for New Jeans and the group which now calls itself Fifty Fifty to chart again in Hot 100. (Ablume is a different story but I don't think it will be easy for them either)
And , because Katseye, not exactly a Kpop group, is doing better, Illit will mostly emphasize its Japanese activities and drift farther from Hot 100
So it is safe to say that the tradition of KPop acts charting in Hot 100 has ended with Le Sserafim.
No SM act, for whatever reason, charted in Billboard Hot 100.
And, of course, I have to say this - no acts from Edam Entertainment charted in Hot 100 as well.
