  We investigate the physical properties of accretion flows around
Konoplya-Zhidenko (KZ) black hole, proposed by deforming Kerr spacetime to
address the inaccuracies in the observation of gravitational waves resulting
from a binary black hole merger. The dynamical equations describing the general
relativistic viscous accreting flow are solved self-consistently to find the
transonic accretion solutions in terms of global constants, such as energy
($E$), angular momentum ($\mathcal{L}$), viscosity parameter ($\alpha$), spin
($a_{k}$), and deformation parameter ($\eta_0$). We obtain five distinct types
of accretion solutions (O, A, $\text{A}^{\prime}$, W, and I-types) and observe
that those solutions are not unique but rather continue to exist for wide range
of parameter spaces in the $\mathcal{L}-E$ plane. Furthermore, we find that the
viscous accretion flows can harbor shock waves when relativistic shock
conditions are satisfied. Consequently, the shock-induced global accretion
solutions are obtained and the effect of $\eta_0$ on shock properties, such as
shock radius ($r_{\rm sh}$) and change in electron temperature ($T_{\rm e}$)
across the shock front are investigated. Moreover, we calculate the spectral
energy distributions (SEDs) of accretion flow using the relativistic thermal
bremsstrahlung emission coefficient and study the modification of SEDs due to
the increase of $\eta_0$ for both shock-induced and shock-free solutions. In
addition, it has been noticed that the observable quantities, like
quasi-periodic oscillation frequency ($\nu_{\rm QPO}$) and bolometric disc
luminosity ($L$), are strongly depend on $\eta_0$. Finally, we
phenomenologically show that the KZ black hole is consistent with the observed
high-frequency QPOs, commonly observed in black hole binaries and black hole
candidates.
