See https://commons.wikimedia.org/wiki/File:Annie_Besant_-_The_Story_of_Afghanistan.pdf
Click link for 677 × 1,031 pixels in:
//Size of this JPG preview of this PDF file: 393 × 599 pixels. Other resolutions: 157 × 240 pixels | 315 × 480 pixels | 677 × 1,031 pixels.//
(the correponding Url is https://upload.wikimedia.org/wikipedia/commons/thumbhttps://upload.wikimedia.org/wikipedia/commons/thumb/e/ed/Annie_Besant_-_The_Story_of_Afghanistan.pdf/page1-677.08333333333px-Annie_Besant_-_The_Story_of_Afghanistan.pdf.jpg
Result:
404: Not Found
It is also weird that page size is represented as float.
It has been changed recently by this commit:
https://gerrit.wikimedia.org/r/#/c/mediawiki/extensions/PdfHandler/+/560127/2/includes/PdfImage.php
with no comments.
Has it been done intentionally?
This creates problems, e.g. see https://en.wikisource.org/wiki/Page:Annie_Besant_-_The_Story_of_Afghanistan.pdf/15, where the image thumb url points no a not existing page.