Unknown Addon in Singleplayer

There is this unknown addon that I MAY have installed, though I have no idea what use it has. If any one could tell me what purpose it serves or how to remove it, please inform me. Thank you.

An addon that identifies entities through surfaces? Seems broken, just remove it by going to your addons folder and deleting it.

If you downloaded it through the workshop, unsubscribe from it.

Problem is, I have no idea what addon it is so I don’t know which.

Disable each addon one by one until you isolate which one it is.