**System Information**
Operating system: Windows 10
Graphics card: NVIDIA RTX 2070 Super
**Blender Version**
Broken: 2.91
Worked: (Nothing since collection system was presented)
**Short description of error**
Objects with volume material is included in render even when it's inside HOLDOUT collection.
Apart from the question whether volume material should mask the other collections, it should not be rendered like it normally would. It should at least be excluded from the render.
(Volume material object inside INDIRECT ONLY collection works fine)
**Exact steps for others to reproduce the error**
It's very simple. Based on the default new file...
1. Make a new collection and enable holdout.
2. Make a new icosphere object inside the new collection.
3. Give the icoshpere a volume material(Simple principled volume is fine).
4. Move the icosphere in front of the camera, making the default cube go behind the icosphere inside the camera view.
5. Render the image. You'll see that the holdout is not working properly for volume material objects.