Currently, Confluence does not allow users to directly copy URI Code and paste in Confluence page. For example, the following image: https://dopiaza.org/tools/datauri/examples/index.php, copy-pasting the image won't work and will appear as a broken image as the screenshot below.

To make this feature work, users would need to add an HTML macro which is an extra step to be done rather than just copying and pasting the image directly to a page.