washed out textures in render I have seen some similar questions, but I don't think my problem is that I have overlapping faces. I have also tried adjusting the lighting level but the problem persists. When cycles render preview does 1 or 2 out of the 32 render cycles then the coffee looks more or less correct but the end result is always grey and white and washed out. I might be able to fix this with an overlay of color in the nodes, but is there any way to avoid the problem in the first place?


render preview
blend file https://drive.google.com/file/d/17M1Bm2xdQxLtuhR7DOEmqay4WGezRiSE/view?usp=sharing
UPDATE: I turned the light intensity down and changed to darker base colors for world and sun light sources. I changed the base color of glass and coffee which improved the glass slightly, but the coffee is still ridiculously reflective. I have roughness at .5 and turning it up to 1 does not help.

Final result after applying instructions in checked answer

and after adding a transparent BSDF and decreasing transmission and increasing roughness of glass

I also decreased the light intensity for world and both lights to .4 for world and about 100 watts for each light down from 600
Final version -- https://drive.google.com/file/d/1z5UkbsWIKdtGmvthzcef6k3zenHixaNm/view?usp=sharing
Your environment lighting (world and light) was very bright. So first thing, change your lighting. Also, your coffee material has a Transmission of 1, which makes it reflect the environment like a glass, and a Roughness of 0.55, which makes the reflection scattered all over the surface, it's not what you expect from water, and it creates a rather grey material, you can't see the Volume Absorption effect any more.

If you don't want this scattering effect, which would make more sense, low down the Roughness value:

You can also mix your BSDF with a Transparent node to lown down the glass effect: