Some of the Publii search plugins can generate search results as a separate area. In order to properly handle this feature you must implement two changes in your theme:
1. Add support for customSearch
customSearch under your theme supportedFeatures section.
2. Implement @customSearchContent global variable
In the simplest for you must just add the following code in your theme to the search.hbs file:
Then plugins which uses this global variable, will output there search results.