why has a sandbox with page composer changes affected a page WITHOUT publishing it?

Summary:

i recently did some testing in sandbox with page composer on our disability info view other's info page. I set the sandbox to not publish because i definitely didn't want these changes to be reflected in the TEST environment. However, The changes showed immediately without publishing! I've tried it a couple of times, removing a field and it immediately removes the field even though i didn't publish the sand box

Content (please ensure you mask any confidential information):

Version (include the version you are using, if applicable):

24D some redwood (but not the page i was working with)

Code Snippet (add any code snippets that support your topic, if applicable):