Modifying page titles in large numbers can have a negative impact on indexed rankings, but as long as the changes are reasonable and not too frequent, the impact is usually manageable.

Search engines usually determine the topic and relevance of a page based on the page title and use it as an important factor in ranking. If the page title is frequently modified, search engines may perceive the content of the website as unstable or untrustworthy, thus reducing the ranking of the website.

However, if changes are made for legitimate reasons, such as optimizing keywords, improving title-content fit, or improving user experience, the impact on rankings can be positive. Reasonable changes can help websites better match search intent and improve the relevance and quality of pages, which can help improve rankings.

It should be noted that when modifying page titles, care should be taken to avoid frequent modifications. Frequent modifications to page titles may lead to a decrease in search engine trust in the website, and may cause search engines to re-evaluate the relevance and quality of the website, thus negatively affecting rankings. It is recommended that when making title modifications, there should be clear optimization goals and strategies, and moderate testing and monitoring should be carried out to ensure that the effect of the modifications is as expected, and to minimize the negative impact on rankings.