I would expect that to be an outlier in the sulfur/sulfuric compounds concentration low to ground, but wouldn't expect it to show up in the NOx concentration sa

I would expect that to be an outlier in the sulfur/sulfuric compounds concentration low to ground, but wouldn't expect it to show up in the NOx concentration satellites pick up (averaged over a fortnight and the whole of the troposphere). And indeed, if I compare the maps of Germany for the timeframe 23-12-2019 - 06-01-2020 with the one of 16-12-2019 - 30-12-2019, then I fail to see any reminiscence of the Sylvester Nacht.