  We investigate and report the effects of rainbow gravity on the spectroscopic
structure of KG-oscillators in a mixed magnetic field (in the sense that it has
the usually described as a uniform and a non-uniform magnetic fields, each at a
time) introduced by the 4-vector potential $A_\mu=(0,0,A_\varphi,0)$, where
$A_\varphi=B_1 r^2/2+B_2 r$, and $B_1$ and $B_2$ are magnetic field strengths.
We also discuss and report the effects of such a mixed magnetic field on the
spectra of KG-oscillators in cosmic string rainbow gravity. In so doing, we
introduce a new and quite handy \textit{conditionally exact solution}
associated with the truncation of the biconfluent Heun functions into
polynomials. Using a loop quantum gravity motivated rainbow functions, we
observe interesting effects when the magnetic field strength $B_2$ grows up
from zero. Such effects include energy levels crossings which, in this case,
turns the spectra of the KG-oscillators upside down. Moreover, Landau-like
signature on the spectra are observed and discussed. Yet, interestingly, we
also observe that rainbow gravity affects the magnetic field as well, in the
sense that the magnetic field becomes probe particle energy-dependent one.
