I have used Confluence professionally at different assignments for many years and now in version 1000.0.0-92fa487229c1 I get this big white space below my embedded Draw.io-diagrams so that the Page is extra long and need to be scrolled up and down.
The extra space is not shown in Edit-mode of the Page.
I have tried "Full width setting" and "Fixed width" setting on the Page, different Viewer settings on the Diagram-image/frame and different Page layout settings inside Draw.io. Creating new embedded Draw.io-diagram have the same problem as soon elements are added in the drawing making it long/wide.
Nothing makes the extra white space on the Confluence Page go away.
The same ugly space is there also in a different web browser.
It has something to do with the width of the drawing, adding elements making the drawing wide (about 4 standard pages wide, but the page size or no page size does not affect the problem) and Publish will make the diagram-image on the Confluence Page zoom/adjust so that the whole drawing is shown. It can look OK first and you Edit the Page and write some text directly below the drawing and Update. The Page looks OK....but press Ctrl+F5 to reload the web browser... then you will see a big white space between the drawing and the text! The space between is about three times as high as the height of the drawing-image. Does Confluence make room as if the drawing was square or something like that?