How did my friend get doxed?

A friend of mine whos 29, recently got doxed online and we are both curious as to how they found his address? The person who doxed him had very little information. The only information the doxer only had was his Epic Games ID, Battlenet Tag, Youtube Channel, Discord User, Spotify, Instagram and Twitter. All sources had zero personal information provided and both Instagram and Twitter were both 100% private and no new followers were accepted. No links/phishing were clicked on. …

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