In fact, what you want to know is how others know your QQ number and your name. There may be several reasons:

The trumpet number of an acquaintance around you: He knows Your QQ account has added you again. Maybe it’s someone who admires you and doesn’t want you to know who it is?

The number of a friend of your acquaintance: I got your QQ number through your acquaintance. He must have added you because he wanted to make friends.

You leaked your information: you left it somewhere inadvertently, for example, someone replied to your name in your QQ space, and people saw it, so they knew it.

Hope this helps.