Since macOS 26 (and now in 27) I have experienced an issue where most images do not display in Wikipedia in the native Dictionary app:
The only ones that do appear correctly are small images stored on the Wikipedia servers only in their original resolution, as opposed to a reduced-size preview (see e.g. top and bottom images from the attachment above).
I have the same issue on multiple computers running different operating systems; restarting and removing/readding Wikipedia to the list of Dictionary sources did not help. Can anyone suggest a fix?