Unity 5 Directional Light Shadow Flicker

The issue is the camera draw distance. Select your cameras, and Reduce the far clipping from current to 3000 or less and it should disappear. Had the same issue for almost a week. Nothing helped, then I added a new camera, and it was gone. Reverted to save, added the new camera and compared. The only difference was the far clip.

After spending many hours trying to figure out why shadows were flickering on all my devices with A11 chips (iphone 8s and X), and trying everything on this forum as well as many others, I finally fixed my issue by setting the 'render mode' of the lights in my scene that cast shadows to 'Important' (old setting was auto, which explains why sometimes the issue was present and sometimes not). In my scene I only have one light casting shadows, so it works to set it to important.

////// Other things I tried that did not fix my issue - adjusting cascades - adjusting biases - adjusting near/far clip planes - adjusting color space (linear or gamma) - adjusting resolution - adjusting shadow fit

Not sure if this is helpful, but I noticed that I would get a lot of Directional light shadow flickering if the Rotation of the Directional Light was set to something like x = 90, y = 0, z,= 0. So I had my light pointing straight down which produced the flickering. I fixed this by giving the light a small rotational offset and the flickering went away.

Change shadow projection to close fit.