There is no written information about how warnings might affect your search ranking. If you received the warning for creating a gig and you create a gig that violates the ToS again, you may have your account closed on Fiverr.
Other than that, warnings specifically affect your ability to achieve and maintain levels. You can read about it here and here is a brief summary:
“Above all, we aim to keep our marketplace safe and fair. Any seller who violates our terms of service receives a warning—and if the offenses continue, the seller may be removed from Fiverr. In the updated system, sellers must ensure they’re not violating our rules or risk a level drop.”
You would need to give more information about what the warning said and what kind of gig it was if you want a better answer.