When sorting by relevance, the results are ordered based on how well they match the given search phrase. This ensures that the most relevant results appear at the top, with less relevant results sorted at the bottom.
More on ranking can be found here.
However, if you sort by a different criterion (e.g., by lowest price), we cannot guarantee that the top results will be highly relevant to your query. To address this, we adjust the results on the backend by removing less relevant matches (e.g., those that match the phrase only in the description) and returning a new set of results.
If your search phrase is very broad, this may result in a larger number of "removed" results. Despite this, our approach ensures that the results remain useful and increases the likelihood of clients making a conversion.
We understand this behavior might seem unusual at first. However, it is a common practice among search engines.