Smoothing kernels for the QC metrics are wack

[LTLA]

According to kana:

But according to R:

There shouldn't be so much density at 14-ish. This is confusing because I was worrying that the entire bulk of cells was being filtered out, but it turned out not to be so.

Also the filter threshold is at 15.3 here and that doesn't look like it on the plot.