Distribution of ﹩{\delta }_{F}^{\mathrm{pc}}﹩ derived from the method in Section 3.2. We include all nine protoclusters in the overlap of CLAMATO and COSTCO volumes. The blue histogram is the distribution of ﹩{\delta }_{F}^{\mathrm{pc}}﹩ in 1140 COSTCO-FGPA mock realizations, the orange line marks the ﹩{\delta }_{F}^{\mathrm{pc}}﹩ of the corresponding protoclusters in the observed CLAMATO, and the gray vertical dashed line represents ﹩{\delta }_{F}^{\mathrm{pc}}=0﹩. We highlight COSTCO-I with bold text (center panel); the mocks for this structure are clearly inconsistent with the CLAMATO measurement.