These files are primarily used in attacks. Threat actors load the list into "checkers" or "brute-force" software to see which accounts are still active and do not have multi-factor authentication enabled. Once an account is validated, it is often sold or used for:
The tag @BigDataCombo refers to a specific Telegram channel known for sharing databases and automated account-checking tools. 30k Combo Yahoo Uhq @BigDataCombo.txt
Gaining access to other services (Amazon, Netflix, etc.) linked to that recovery email. These files are primarily used in attacks