Yeah that is common when using denoise, which is why I never use denoise in final renders, I just crank up the settings so I can get the cleanest render possible and finding the right balance so it doesn’t take a month of rendering. So in other words, don’t use the denoiser, just do some good old waiting for the image to clear up as much as possible with samples. Also remember there’s services like Sheepit where you can speed up your renders.
