Your browsing history will be accessed and then processed on the third party server. After your session is over all the data will immediately be deleted from the server.
You have to consider that color pin will reveal a general nature of the data and knowledge you interacted with - it will reveal it as a color map. We want to keep the map imprecise and intuitive. The goal of the color pin is to give you a broad understanding of the data you own and knowledge you interact with. You can keep it private or you can share and compare it with your friends.