bright pixels on material and reflections behave like transparency

[lextorlex]

Hi, Can someone help me understand the reasons of appearing of bright pixels (red arrows) and why reflections behave like transparency (green arrows) on curtain materia which has no transparency at all?

[maru]

Bright pixels - this may be happening because of the object not having thickness. Adding "shell" modifier might help.

"Reflections" - this looks more like incorrect geometry. Some overlapping faces maybe?

[romullus]

Can you show curtain material screenshot? To me, red arrows looks like reflections of light sources, green arrows looks like translucency.

[lextorlex]

Here is material in slate and 8 minutes rendering of CESSENTIAL_Reflect render element