Some users don’t see latest changes after Preload

Hi,
After making significant changes to my website like updating plugins or page templates, I use the Preload feature to refresh the cache so that users see the latest changes right away. However, I had some users reporting that they still see the old version in multiple browsers, incognito windows and even while logged in (cache is disabled for logged in users in settings), while others see the latest cached version. Doing a hard refresh in the browser also doesn’t seem to help. The only thing that helped was manually deleting the cache before the preload, which is strange because the old cache is supposed to be cleared after the preload is completed anyway. I was unable to replicate the issue in order to get to the bottom of why that happens. Any idea what could cause this seemingly random behaviour?