This might be happening because of how ZeroBounce handles "catch-all" emails by default. Catch-all emails are automatically marked as valid, even though there may be uncertainty about whether they belong to the specific individual or if they're aliases.
To fix this and be more conservative in your email validation, you can enable the "Only Safe to Send" option in your ZeroBounce settings. When this toggle is activated, only emails that are specifically categorized as "valid" will be returned as valid, excluding catch-all emails.