  We give evidence that fully supersymmetric Anti-de Sitter vacua of extended
supergravity with a residual gauge group containing an abelian factor cannot be
scale separated as a consequence of the weak gravity conjecture. We prove this
for N=2 and N=8 supergravity and we explain how our argument applies also to
vacua with partially broken, but extended residual supersymmetry. We finally
discuss possible loopholes and especially how certain N=1 models can evade our
reasoning. Our results suggest that N=0,1 supersymmetry at the lagrangian level
might be the most promising chances to obtain a truly four-dimensional
effective description of quantum gravity.
