Weird shadows artefact

As you can see on the attached screenshot, I have a very weird result in my viewport and this is the same thing for any scene that comes from my project. It seems not to be related to the directionnal light or skylight (set as movable). This result occurs even I disable these source lights or their “cast dynamic shadows” parameters,…
The “shadow stips” are moving proportionnaly to the distance of the camera.
Is there something in a mysterious cache,… ? Any help would be very very useful.
Thanks !

hlx

Check your Light Source (DirectionalLight) actor settings. I had similar effect when I changed Shadow Bias, Shadow Filter Sharpen and Length - they connected in effect, so tweak it some. It can be also connected with your material settings, but rather this three settings in Light Source.

And check how it looks after light rebuild. I think this is more light settings, but terrain shadows can look different after rebuild.

More - I see it is in some volume - post process or this Fog2 - maybe here also changes, but in my case it was Light Source settings.