Covariance matrix of void counts and stacked void-galaxy cross-correlation function (monopole, ξ₀, quadrupole, ξ₂, and hexadecapole, ξ₄), computed via 100 PATCHY mocks. The matrix is normalized by its diagonal components and the two panels correspond to the redshift bins used in this analysis. The solid black lines divide the void size function data vector with the void-galaxy cross-correlation function ones, while the dashed lines separate the different multipoles from each other.