My player frame still highlights when targeted despite having Player->Other->Highlight options disabled. Not sure if there's another option I'm missing that needs to be turned off, but I can't seem to find one after a bit of searching. Using the latest version as of post time from wowaceupdater.
The highlight module highlights a frame when you have them targeted or have your cursor over them. In yellow. The BanzaiAlert module puts a red glow on a frame when they have aggro. I believe it tells you this in the tooltip.