Radio spectral indices at 22–43 GHz and 43–86 GHz. The top panel represents the values derived from the CLEAN total flux, while the bottom panel corresponds to the active flux. The orange scatters represent the spectral index at 22–43 GHz, while the green scatters indicate the spectral index at 43–86 GHz. The horizontal dashed line indicates that the spectral index is zero, and the dotted line in the top panel is the mean value with α = −0.6. In the bottom panel, the orange dotted line represents the average active spectral index of −0.19 at 22–43 GHz, while the green dotted line represents the average active spectral index of −0.37 at 43–86 GHz. The gray box indicates the decreasing period from 57124 to 57636 at 43 GHz.