This paper investigates the effects of rainbow gravity on the spectroscopic structure of Klein-Gordon (KG) oscillators in a mixed magnetic field, introduced by a 4-vector potential \( A_\mu = (0, 0, A_x, 0) \) with \( A_x = B_1 r^2/2 + B_2 r \), where \( B_1 \) and \( B_2 \) are magnetic field strengths. The authors introduce a new conditional exact solution for the biconfluent Heun functions, truncated to a polynomial of order \( n_r + 1 \). They observe interesting effects as the magnetic field strength \( B_2 \) increases, including energy level crossings that flip the spectra of the KG oscillators. Additionally, they find Landau-like signatures on the spectroscopic structure and note that rainbow gravity affects the magnetic field, making it energy-dependent. The study uses loop quantum gravity-inspired rainbow functions to ensure that the maximum allowed energy for particles and anti-particles remains below the Planck energy scale. The paper provides a detailed analysis of the effects of both rainbow gravity and the mixed magnetic field on the KG oscillators, contributing to the understanding of quantum systems in cosmic string spacetime.This paper investigates the effects of rainbow gravity on the spectroscopic structure of Klein-Gordon (KG) oscillators in a mixed magnetic field, introduced by a 4-vector potential \( A_\mu = (0, 0, A_x, 0) \) with \( A_x = B_1 r^2/2 + B_2 r \), where \( B_1 \) and \( B_2 \) are magnetic field strengths. The authors introduce a new conditional exact solution for the biconfluent Heun functions, truncated to a polynomial of order \( n_r + 1 \). They observe interesting effects as the magnetic field strength \( B_2 \) increases, including energy level crossings that flip the spectra of the KG oscillators. Additionally, they find Landau-like signatures on the spectroscopic structure and note that rainbow gravity affects the magnetic field, making it energy-dependent. The study uses loop quantum gravity-inspired rainbow functions to ensure that the maximum allowed energy for particles and anti-particles remains below the Planck energy scale. The paper provides a detailed analysis of the effects of both rainbow gravity and the mixed magnetic field on the KG oscillators, contributing to the understanding of quantum systems in cosmic string spacetime.