We can see the anomaly in SO2 actual from the NASA data itself: https://so2.gsfc.nasa.gov/pix/special/time_sres/time_series.html
This clearly shows some crazy spikes right then and there for Eastern Asia. Look at the scale, ffs, its off the charts:
And there's also a weird data hole around Feb 2 (0 everywhere).
Doesn't mean we know what it was from, but it cannot be denied that there are/were crazy spikes in SO2 over that region recently.