Splotches on curtain

As you can see I’m geting splotches on the curtain… any idea of what might be causing this?
It’s a simple material with translucency.

The scene is attached.
SUITE1_009.max (3.59 MB)

sheers are too close to wall.

That can’t be the problem, I’m sure. The curtains are a few centimeters away.

Did you checked it before claiming? sheers are moved by 40cm away from wall

What I ment was the problem cannot be the curtains are too close to the wall for Corona must be able to handle these kind of normal situations. It’s a real world thing, not something weird like two coincident planes.

your problem will be fix if you increase Record quality to something like 5000 or 6000 in HD cache setting .

You are right. I had already tried to increase the quality to 2048 and it looked almost perfect.