There is a workaround to set r.VolumetricRenderTarget.Mode=1.
The lines appear to be coming from the temporal component of the Volumetric Clouds. Each
frame, the lines are merged in from the previous one.
1. Create a new empty project using Unreal Engine version 5.3.1.
2. On the default map, add a flat plane (or any mesh of your choice) and scale it up
significantly to resemble a massive object, like a planet.
3. Position your viewpoint so that the Volumetric Clouds are below you, and you can see
clouds that are in front of the scaled-up mesh.
4. Enable the setting: r.VolumetricCloud.HighQualityAerialPerspective = 1.
5. Observe the flickering horizontal lines
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-198490 in the post.