I run a process in a background (i.e. nobody attached) GNU screen session on a fresh Kubuntu machine (in a qemu vm). It starts very early during boot, runs for many minutes, and creates all kinds of output. Potentially that can be everything. At least it includes ansi escape sequences for colouring.
Later on, when I'm logged in to kde, start konsole and attach to it via 'screen -x', I get endless flickering. You can see some piece of output, but you can see how it builds the screen from top left to bottom right, character by character, then it instantly jumps back and repeats, and repeats, and repeats. Many times a second, so quite fast. Always with the same piece of output. It completely ignores any user input. In its 'status bar' I see 'Copy mode aborted' all the time.
In its current process state at that time, it should just show a prompt for user input and should not generate any new output at all.
Do you have an idea why it has that behavior here instead of just showing me the last output lines and the prompt I've mentioned?
