  In the last decade Planck PR4 data together with ground-based experimental
data such as, BK18, BAO and CMB lensing, tightened constraint of the tensor to
scalar ratio, starting form $r < 0.14$ to $r < 0.032$, while the spectral index
lies within the range $0.9631 < n_s < 0.9705$. Viability of modified gravity
theories, proposed as alternatives to the dark-energy issue, should therefore
be tested in the light of such new result. Here, we explore $F(R,G)$ gravity
theory in regard of the early universe and have shown that, it is not
compatible with newly released constraints on $r$ and $n_s$ simultaneously.
Further, it also fails to produce a feasible radiation dominated era. It
therefore questions the justification of using the model for resolving the
cosmic puzzle.
