That’s the shimmering/watery reflections in cockpit and other external parts of the vehicle. It’s the RT not being implemented properly. Topic is being discussed to death in another thread as we speak! Sorry, can’t find the link.
As said above this has already been discussed /reported. The RT sample count is simply way too low (reflections & AO) the denoiser can’t make miracles. RT simply shouldn’t be applied in cockpit view given how bad the implementation is.