Copy / Pasting not working properly in ID20

Data exchange like the clipboard here, but also drag and drop, comes in flavors.

That is, the source provides text, utf, rich text and so forth for text and the destination chooses what's best to them.

For page items that includes internal objects stored in a scrap area, snippet, PDF and TIFF, you likely get one of the latter.

Third party export format plugins may add their own flavors. Are you using any one of those? Declaring the appropriate priority is tricky.

The "Copy" process has multiple phases, internal flavors differ from external flavors.

For performance reasons, as long you stay within InDesign the data is not exported to the external clipboard.

So the first step is to strictly stay within InDesign, not switch over to other applications.

You don't sound like you did, but do you have any extension (CEP) panels open that might trigger externalization?

There could also be different applications that request such an externalization in order to perform changes on the clipboard.  Never heard about them, but search points to Maccy, Flycut, CopyClip, ClipMenu. Does any of them sound familiar? Maybe a new security annoyance, or something to hand over the clipboard to a mobile device?

Instead of copy paste, you could also try drag and drop as its externalization is triggered in different ways (external windows). Any change there?

If you drag your page items to the desktop, does that produce a snippet or also the picture?

What's your operating system version? Also, do you have the same issue in InDesign 2024?