Chiral ring along the RG flow in 5d $\mathcal{N}=1$

We compute the Higgs branch chiral ring of a simple class of 5d theories at strong coupling. A deformation by the instanton mass implies that the chiral ring at weak coupling is renormalized by a nilpotent operator, the gaugino bilinear. Consequently, F-term equations alone do not suffice to completely determine the moduli space of vacua and perturbative non-renormalization arguments are invalidated.