I'm not sure what to search to find information about it, but when a program gets a "User wants to copy this" request, the program can add multiple types of data to the clipboard. Say, one type is plain text, another is formatted text, etc.
That way, if the program receiving the Paste request supports the "fancier" version it can use that or fall back to the plain text version if it doesn't.
In macOS, there is a default system wide shortcut key to paste plain text: ⌘+⌥+⇧+v (cmd, option, shift, v). This is shown in the Orion "Edit" menu as "Paste and Match Style".
How to Strip Formatting When You Copy and Paste Text: 5 Ways
There are programs that exist only to prevent the rich text copying like Pure Paste — Sindre Sorhus
You can see this in action:
- copy a link from hacker news, like above
- open https://www.editpad.org/tool/online-rich-text-editor
- create a new note
- press ⌘+v to paste the title as a link
- press ⌘+⌥+⇧+v to paste just the link url
It's not really a bug, this is operating as designed. When you paste and "just the title" shows up, it should still be a clickable link in that program.
There is a program called Clipboard Viewer from Apple in the "Additional tools for XCode" package. It shows that there are 10 different types of data set to the clipboard when I right click -> copy a HN article link.