Finite-dimensional signatures of spinodal criticality are notoriously difficult to come by. The dynamical transition of glass-forming liquids first described by mode-coupling theory is a spinodal instability preempted by thermally activated processes that also limit how close the instability can be approached. We combine numerical tools to directly observe vestiges of the spinodal criticality in finite-dimensional glass formers. We use the swap Monte Carlo algorithm to efficiently thermalize configurations beyond the mode-coupling crossover and analyze their dynamics using a scheme to screen out activated processes in spatial dimensions ranging from d = 3 to d = 10. We observe a strong softening of the mean-field square-root singularity in d = 3 that is progressively restored as d increases above d = 8 in surprisingly good agreement with perturbation theory.
