Dunno, right now they are once again the cheapest biz seats ex-Tokyo to quite a few destinations. Was fairly regularly like that pre-pandemic so was only a matter of time before that came back. I don't think any of the mainland carriers are even close to being back to full schedules to the US yet, nor are US carriers back in full force to China either. Suspect it's much deeper than just the past lockdowns. I don't know how soon, if ever you're going to see $2400 again but prices between the US and East / NE Asia are still extremely high while a lot of the rest of the world has cooled down. You might be better to look at some options going eastward via Europe or the ME instead for the time being.