Thanks for the tip OP, although still tempted and not pulled the trigger yet.

I was hoping this deal would go beyond March, even April 23 would do the wonder but SK doesn't even have fares loaded beyond March 31st, 2023.

In addition, to get this deal your starting point has to be one of SK's US gateways (EWR, ORD, IAD, MIA, LAX, SFO), any connections from other cities would triple the fares, in some cases even more than Business Class (DTW for example), so it's worth driving to those gateway airports (ORD in my case) to save $$. Lastly, open-jaw is allowed, I tested ORD-HEL, BGO-ORD and those low Plus fares showed up.