  Scattering processes in quantum materials emerge as resonances in electronic
transport, including confined modes, Andreev states, and Yu-Shiba-Rusinov
states. However, in most instances, these resonances are driven by a single
scattering mechanism. Here we show the appearance of resonances due to the
combination of two simultaneous scattering mechanisms, one from
superconductivity and the other from graphene p-n junctions. These resonances
stem from Andreev reflection and Klein tunneling that occur at two different
interfaces of a hole-doped region of graphene formed at the boundary with
superconducting graphene due to proximity effects from
Bi$_2$Sr$_2$Ca$_1$Cu$_2$O$_{8+\delta}$. The resonances persist with gating the
from p$^+$-p and p-n configurations. The suppression of the oscillation
amplitude above the bias energy comparable to the induced superconducting gap
indicates the contribution from Andreev reflection. Our experimental
measurements are supported by quantum transport calculations in such
interfaces, leading to analogous resonances. Our results put forward a hybrid
scattering mechanism in graphene/high-temperature superconductor
heterojunctions of potential impact for graphene-based Josephson junctions.
