A unified study has explored the quasinormal modes (QNMs) of Schwarzschild black holes corrected by a Gauss-Bonnet (GB) term in higher dimensions. Using a high-precision Chebyshev spectral method, researchers mapped the QNM spectra across $D\in\{5,6,7,8,10,11,12,26\}$, extending beyond the reliability of sixth-order WKB and characteristic-integration techniques in high-precision regimes. The findings reveal robust signatures of higher-curvature dynamics, including the appearance of overdamped purely imaginary modes and non-monotonic behavior in the real parts of higher overtones.

In the scalar and vector sectors, the study uncovered an exact isospectrality between the scalar monopole ($\ell=0$) and vector dipole ($\ell=1$) at vanishing GB coupling. This finding is supported by an analytical proof based on a Darboux factorization of the corresponding Hamiltonians. Furthermore, in the tensor sector, the first numerical confirmation of a long-predicted instability in six dimensions was obtained; its onset is sharply captured by the Cohn-Calogero bound, leading to a mass threshold of $GM\leq 158.1\,\alpha^{3/2}$. No analogous instability was found for $D\geq 7$, and no tensor isospectrality occurred.

Converting the dimensionless frequencies to physical units suggests that the amplified modes in higher dimensions may enter the sensitivity window of future space-based detectors such as DECIGO. This comprehensive analysis provides a benchmark for QNMs in Einstein-Gauss-Bonnet gravity and highlights the limitations of standard approximation schemes in the strong-coupling and high-overtone regimes.