How to determine the ID of any Vkontakte user on any site?

Question

In contact with

Good afternoon , I was recently chatting on the betscsgo.net website, talking with random users, and suddenly I received a message on Vkontakte from one of the users of that chat. On that site, he himself did not leave a link to his Vkontakte profile - this is 100%, and if I'm not mistaken, there is no link between Vkontakte and the profile on the site. I tried to find out from him, but he does not tell, but I am terribly interested.
Part of the correspondence:
His Vkontakte: https://vk.com/14ugent88
Question: how did he (an ordinary user) identify my VK page?

Answer 1

xss vulnerability on your roulette site, or the person is connected to the owners.
the page is determined through services such as socfishing or similar scripts.

Answer 2

Googled it. Your page vk.com/mrfallen92