Use less denoise than 1 (usually 0.5 or 0.6 is recommended, with enough passes for that). Alternatively, add an additional Beauty render pass, and set it not to use denoising (or, some denoising but significantly less than the main Beauty), and blend in post using a mask (manual, or you could use an object id mask in the render passes too). "Blurring" is of course just what a denoiser does, and finding the right amount is the balance between blurring the noise and not blurring details - and sometimes the blending in post between different denoising is the easiest solution.
(Or of course, use no denoising and render enough passes to clean the image without it, is an option too).
