Sandra “clicked a button” the other day, and noticed a cool feature in the Page details option at the top of a SharePoint Online page. You can examine the version history of the page, and see what web parts were edited or deleted. Here’s how that works…
When you’re on a SharePoint Online page, click on the Page details option:

On the right side of the page, you’ll see the Page details panel. Scroll all the way down to the bottom and click on Version history:

Each of the changes has an entry in the Version history. Turn on the Highlight changes on the page option, and click on one of the Published entries to expand it. In my example of version 165, the Hero web part was edited and the Quick chart web part was deleted:

When I look at the Hero web part, I see the Edit icon in the upper-left corner:

And in the Quick Chart web part, I see the Delete icon:

This is a quick way to check out the version history of a page to see who changed it and what was changed.