“…Indeed, in the zeta-function-based spectral Lagrangian the only allowed gravitational term would be the Weyl tensor square, what is nothing but a classical Lagrangian of conformal gravity 30 . This higher derivative gravitational model is renormalizable by 30 In general, the zeta-based scale-invariant spectral Lagrangian may contain φ 2 R and φ 4 terms, where power counting, and, what is also important, PT-symmetric. Generally speaking the higher-derivative theories are non unitary, however, a presence of the PT-symmetry allows to quantise it in a unitary way [102], using the PT-symmetry Bender-Mannheim formalism [21,101], see also [8,[106][107][108] for the recent progress PT-symmetric studies in particular in the context of the noncommutative geometry [109].…”