Search inputs are synced accross applications, how to disable? [duplicate]

A colleague of mine has macOS 10.15 (Catalina) and complained about the following thing: He uses the search bar in Mail and searches for something. Then in Xcode he presses CMD+F and sees the same email address there as the search input. We have checked and that is not in the system clipboard.

This synchronization of search strings might be a helpful idea, but in practice it does not make sense to search for things across applications. Is there some way to disable this behavior?

Solution 1:

Search input uses the same 'hidden' copy buffer that unix uses in Terminal, called the 'kill ring'. The 'kill' command has a second part, called 'yank'

These are used on text editors/terminals/emacs etc using Ctrl ⌃ K & Ctrl ⌃ Y

In effect they are copy & paste, they just save to a different buffer than the regular. As far as I'm aware you cannot disable them, only replace the content with the next 'kill', the same as the regular Cmd ⌘ C & Cmd ⌘ V copy/paste.

How to Geek has a good explanation of how to use it, though not hot to disable it.
How to Use macOS’ Built-In “Kill and Yank” as an Alternative Cut and Paste