The Yandex robot might exclude pages from the index for the following reasons:
The Excluded pages section displays pages that the robot accessed but didn't index (these may include non-existing pages, if they were previously accessed by the robot.)
A page is removed from the excluded list if
The existence or number of excluded pages in the service does not affect the site's ranking in Yandex Search.
Information about the reason for excluding a page from the index corresponds to the time when the page was last indexed by the robot. Wait for the robot to re-index the excluded page.
Headers that the robot requests from the server differ from the headers that the browser requests. So excluded pages might open correctly in the browser.