Article preview isn’t showing changes

I’m having the same issue with published pages and posts. If I try to preview the changes, they won’t show up in the preview environment. I either have to unpublish the page/post or revert back to the classic editor.

I’ve tested this on multiple sites using different themes, different web hosts, and different plugins. I’ve also disabled each plugin one by one with no luck. Additionally, my sites are all using the most up-to-date version of PHP.