  We investigate textbook QED in the framework of the exact renormalization
group. In the strong-coupling region, we study the influence of
fluctuation-induced photonic and fermionic self-interactions on the
nonperturbative running of the gauge coupling. Our findings confirm the
triviality hypothesis of complete charge screening if the ultraviolet cutoff is
sent to infinity. Though the Landau pole does not belong to the physical
coupling domain owing to spontaneous chiral symmetry breaking (chiSB), the
theory predicts a scale of maximal UV extension of the same order as the Landau
pole scale. In addition, we verify that the chiSB phase of the theory which is
characterized by a light fermion and a Goldstone boson also has a trivial
Yukawa coupling.
