What I found isn’t really a solution, but more of a work-around. I realized my foliage was flickering when the directional light was the only light hitting it, but when I added a point light or rectangular light so that it was hitting it too then the flickering was reduced greatly. The main thing is if your scene is supposed to only be lit up by the directional light then adjust the intensity and placement of the point or rectangular light so it blends in with the scene and isn’t noticeable. I’ve found the easiest way to do that is to position the directional light so it’s pointed directly at the flickering foliage. That way that area is so bright that even a point or rectangular light with default intensity will still blend in really well.