There is no such feature but we’d all like it
Ok you can visually unfold the entire Navigator tree to try to spot purple elements… In the navigator, click on Body then as many time as you need on the down arrow key while maintaining ALT pressed. It will select one by one all elements in their HTML order, ignoring hierarchy.
If you find nothing, you may have forgotten some properties at page level, some fields used inside of the SEO or OG title or description, or in the RSS of a template page.
You also need to check the custom code blocks at page level, for the same reasons.
You have to be sure no bindings is made from the Settings tab, for colors, images etc…
If you really find nothing, then contact support, they can work some magic sometimes.