Volume artefacts

I am trying to render a fairly complex scene involving volumes, you can see it in the picture below. As you can see, I am having also some bad artifact issues and I cannot understand what’s causing it.

Here is a screen of the render settings:

The atmosphere is a sphere with a principled volume and a sphere gradient to smooth the border.
The clouds are a VDB object with the mesh to volume modifier and 3 volume displacement. THe shader is a simple principled Volume.

Any suggestion?

Thank you in advance! !

a little update… looks like actually the problem might be in the step rate. lowering to .2 for example makes the situation much better, but it drives render times to something not feasible.

Is there some other trick I could try to work around this without driving render times to infinite?

update no.2:
the problem is connected with the use of the VDB object with the mesh to volume modifier. I am already using a very high voxel resolution (1536), but it looks like the voxels create some shading problem:

I tried using a point density texture as an alternative and there are no artefacts whatsoever. The problem exists in 2.91.2 and 2.92. Is it some known limitation of the VDB object or is blender implementation still not perfect?

Had the problem now too, even if the post is older,
Just in case it causes problems again.
In my case, it was the number of Max Transparency Bounces.

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