The last few days, each day there is a big dip and then an upturn

I understand generally what is happening but I don’t understand specifically why in this case now we are seeing this recurring pattern of a big sell off followed by a less big but not insubstantial increase. Can someone explain what’s happening here specifically? (this behavior is happening with the NASDAQ, Dow, S&P500, VXUS, etc, today if you want to see what I mean)