It becomes public information when shared with the public, unintentionally or not. The specific kinds of relationships involved are a big deal. It’s fine to tell a waitress you closed a huge deal and she can even trade on it, but tell your wife and she can’t trade stocks on that information.

“insiders must be breaching a fiduciary duty owed to their corporation when they trade on or tip confidential corporate information. This stipulation almost always means that an insider cannot trade on such information and cannot tip others about it if the insider stands to gain by doing so. https://sloanreview.mit.edu/article/when-is-it-legal-to-trad...

In the case where an unrelated outsider overhears the information that’s public disclosure. And the information no longer needs to be treated by random people as non-public.