Strange flickering on mobile using the directional lights' shadows (black lines).

Questions & Answers
1

So that’s how shadows look like when using the unity editor - everything is okay:
24298-flickering_pc.jpg

and when I import it on my mobile (HUAWEI - Android) i get this strange flickering:
24301-flickering_mobile.jpg

Why does it happen and how can I fix it?

2

could it be your bias? maybe change that to higher values in the shadow settings of the light?