Trying to paste something with a newline now warns that the text I'm trying to paste contains control characters. Might be related to why the newline warning is not working anymore (https://bugs.kde.org/show_bug.cgi?id=438043).
Created attachment 139899 [details] Screenshot
Adding Jonah since he recently refactored the copy&paste code.
A possibly relevant merge request was started @ https://invent.kde.org/utilities/konsole/-/merge_requests/432
This should be fixed now