It's one of the key results from the paper. From the abstract: "In contrast to demographic reconstructions based on mtDNA, we infer a second strong bottleneck in Y-chromosome lineages dating to the last 10 ky."
From the body: "However, the Y chromosome plot suggested a reduction at around 8–4 kya (Supplemental Fig. S4B; Supplemental Table S4) when the female Ne is up to 17-fold higher than the male Ne (Supplemental Fig. S5)."
Indeed, the title does not match the title of the paper, but hopefully makes it more approachable.
From the body: "However, the Y chromosome plot suggested a reduction at around 8–4 kya (Supplemental Fig. S4B; Supplemental Table S4) when the female Ne is up to 17-fold higher than the male Ne (Supplemental Fig. S5)."
Indeed, the title does not match the title of the paper, but hopefully makes it more approachable.