If you turn on Smooth Lighting, place Cobblestone Wall or Mossy Cobblestone Wall, and place a block to it's left, right, top, and bottom, the wall becomes nearly black. Even when you place a torch or other light source in front or behind it, it still pretends there is no light at all. Pics below are taken with smooth lighting on and brightness maxed out.

Also attached is a pic of my home on the legacy Xbox Minecraft and a pic of the Bedrock edition of the same spot in my home. You can see how the lighting bug for the wall really stands out like a sore thumb.

Let me know if you need anymore specific detail about this bug and I'll update this bug report with the new info.

Edit: bump as this is still an issue on the current version of Bedrock. And still no mod or developer response to cobblestone wall being super dark

Edit 2: 1.2.9 still includes this bug but it is not as extreme as before anymore as shown in Screenshot (164).png. This time, I used the Window 10 version and it is still the same as my iPhone SE.

Edit 3: I just remembered this issue with Smooth Lighting and it turns out that it still hasn't been patched. Cobblestone walls still appear near pitch black when having blocks to its left, right, top, and bottom. Even if you place a Torch or other light source in front of it, the cobblestone wall won't match the surrounding light level and appear very dark.