The URL in question has a page title that varies from the initial HTML response to the rendered HTML.
Why is this important?
As Google's documentation states, employing JavaScript to alter the page title is perfectly acceptable:
Yet, this isn't necessarily the best practice for presenting content to search engines.
Rending webpages consumes significant resources and is far slower than accessing source HTML content.
Google adopts a two-phase approach to crawling: an initial review of the HTML response followed by page rendering for a secondary review. The index can change after this second review.
It is critical that the initial HTML response accurately reflects the key elements you wish to be indexed, including the page title.
If the title is being changed via JavaScript, this could mean that Google initially indexes the title from the HTML response, potentially causing a lag before the rendered HTML title is acknowledged.
This issue is exacerbated if the page content and title undergo frequent changes, leading to outdated titles in the Google index.
What does the Optimization check?
The Optimization will activate if there is a discrepancy between the page title in the response and the rendered HTML.
Examples that trigger this Optimization
This Optimization will be triggered if a URL's response HTML