We have not been made aware of any change to the Google Image Search results page, but that's not unusual. This is a user to user forum and Google would not normally advise us volunteer contributors of UI changes.
Previously image search results were limited to about 700 displayed results, regardless of the actual or expected number, with perhaps one or two "Show more prompts". While investigating your reports I'm now seeing only about half of that amount, with no "Show more" prompts.
Please let me know approximately how many results you are seeing for some different image searches. Also include details of which operating system and browser you're using.
Meanwhile, I'll see if I can find out anything from through our Search Community. Please don't expect an immediate answer — from experience, it could take at least a few days to get any response.
Also, be sure to submit feedback direct to Google by clicking "Send feedback" at the bottom of the results page.
Note: I've marked this reply as "Best answer" so it's highlighted at the top of the replies and can be seen by all visitors to this topic. I acknowledge that this issue is not resolved.
