I've seen a few reports online of users experiencing a green tint to the S7+ screen when at lower brightness (ie under indoor lighting).
Mine has the same issue - colours that should be grey look dark green. If I put the brightness up, this reverts to grey, but the screen is way too bright under these conditions to read. I have the screen set to neutral, and changing the refresh rate doesn't affect this.
Anyone else had this problem, or heard whether there is a fix in the pipeline?