What "300", "301" or "302" mean in the AI Search Console?

Answer

The numbers are response codes from the server that's hosting the site you are testing.

Numbers that start with 300 indicate a redirect from one web page to another.

As they're often used for better site experiences (ex, redirecting to a different language, regional information, or message), the AI Search Console considers them to be "successful" requests as it indicates that the particular AI search indexing bot is not blocked.