Background: Photon-induced reactions provide unique data on nuclear fission due to their selectivity on excitations of low-multipolarity. The data, therefore, contributes to a detailed microscopic description of the nuclear fission process. The emergence of high-intensity quasi-monochromatic γ-ray sources opens up the opportunity to fine scan the excitation energy-dependence of fission observables. Purpose: Measuring ${}^{234}$U(γ,f) fragment mass and kinetic energy distributions for several excitation energies ranging from the fission barrier region to the giant dipole resonance. A fission-mode analysis provides information relevant for the potential-energy landscape of ${}^{234}$U. Method: A position-sensitive twin Frisch-grid ionization chamber is used to determine mass and total kinetic energy distributions of the fragments from the ${}^{234}$U(γ,f) reaction using quasi-monochromatic γ-ray beams between 6.2 MeV and 12.8 MeV provided by the High-Intensity γ-ray Source. Results: Pre-neutron mass and TKE distributions and their dependence on excitation energy are analyzed. As expected, two asymmetric standard modes (S1 and S2) dominate the distribution with small contributions from the symmetric so-called super-long mode (SL) within the fission-mode approach by Brosa and co-workers. The weight of the SL mode increases from ∼ 0.35(1) % at 6.2 MeV to 4.59(3) % at 12.8 MeV, while the peak-to-valley ratio decreases correspondingly from $3.0(15)\cdot {10}^2$ to 17(1). Conclusion: The extracted pre-neutron mass distributions agree well with previous measurements. The average TKE decreases above 8 MeV excitation energy, which is associated with a decrease in S1 fission-mode weight, potentially caused by the onset of two-proton pair-breaking. Mass distributions change significantly for different assumptions on average neutron multiplicities as a function of the fragments’’ mass, but general trends depending on excitation energies persist.