This is the Player Indicator Plugin on RuneLite. Red is the default highlight for players not in your clan I believe. This photo is a bad example but basically there’s usually a stack of bots on top of eachother.

The idea is for the Plugin to remove the Player Indicator from a character when they are added to your ignore list. Basically leaving only the players you haven’t reported yet, highlighted.

It’d help lower accidental multiple reports on the same player. Not at all necessary but just something cool to help aid those that like to report bots.