OAI-SearchBot is the crawler that decides whether your pages can appear in ChatGPT's search feature. Per OpenAI, sites opted out of OAI-SearchBot will not be shown in ChatGPT search answers, though they may still appear as plain navigational links.
The common mistake is blocking it by accident with a broad User-agent: * rule meant for scrapers. If ChatGPT visibility matters, confirm OAI-SearchBot is allowed in your robots.txt and not caught by a WAF rule.