I still have no clue how that happened.
Might be worth your time to go to the gaming subreddit on your web browser and then use the development mode of the web browser to inspect all the cookie data.
The company might be putting more information in there than they show on the screen, that could be available to anyone who can do a search on their website for your characters name.
For example, once I was playing World of Warcraft on an alt, and I argued with a tryhard player about being nice to other players. The WoW Armory, when you look up the alt's name, adds in its cookie/memory the name of all the other characters for that same account (to populate a drop-down selection). So that guy started harassing me on my main character without having never knowing its name.