On our site we use the bing search api v5.
Example: When I search for the term music on either our site search or using bing.com search and specifying to search only our site I get 167 total estimated matches and given that we are displaying 20 results per page there are 9 pages worth of results.
The issue is that when I click on page 9 the total estimated results number displays "Displaying 161 - 74 of approximately 74 results." and only shows 4 pages, with no longer any option to click on a page beyond 4. Is there some known bug that could be causing this issue I am scratching my head here.
This is expected - as you move towards the initially promised number of matches - all search engines remove redundant/very similar matches. So, you get fewer results. You can see this behavior on any search engine site - where millions of webpages are indicated on the first page but you get a handful results when you navigate to pages further down.