For basic QC, I generated this density plot of UMI count per cell. The colors represent two conditions. The black vertical line is the cutoff point at nUMI = 200 for low read counts.
My question is, that small dip at the lower left corner of the plot means around 15K-20K cells have a unique density of counts than the majority of the cells. What could it mean? Does it mean doublets? Or something else? I would really appreciate your comments on this.