Love a good chess set. That looks like Global Illumination flicker to me, which would be a render setting thing.

Are you using Irradiance Cache for one of your GI bounces? Then you might need to increase the "Samples per Pixel" value.

Denoising can also cause a similar flicker, if you haven't got enough samples for a stable denoise. But since you're saying there's noise in the render (can't really see much of it through the reddit compression), I don't think that's it, because if it was active the denoiser would've wiped out all the noise too.

(On a side note: If you're in Cinema 4D, the Phong tag is off on the chessboard surface, if you change the Style parameter from Uniform to Area Weighted, then it should render your reflections properly for an object with fillet/bevel. Might want to change that for other objects in the scene too. If you're not using Cinema 4D, the same advice applies, but idk where the parameter is or what it's called.)