For a given graph $G$, Budzik, Gaiotto, Kulp, Wang, Williams, Wu, Yu, and the first author studied a ''topological'' differential form $α_G$, which expresses violations of BRST-closedness of a quantum field theory along a single topological direction. In a seemingly unrelated context, Brown, Panzer, and the second author studied a ''Pfaffian'' differential form $φ_G$, which is used to construct cohomology classes of the odd commutative graph complex. We give an explicit combinatorial proof that $α_G$ coincides with $φ_G$. We also discuss the equivalence of several properties of these forms, which had been established independently for both contexts in previous work.