(Solved) by going to a one display only setup, needed the 2nd monitor for other things.

What causes spurious random lines between rows of characters in Konsole or other terminal emulators? The lines go away if one simply moves the window, but as soon as one begins sending characters to the tty they randomly come back 2-5 lines on the screen in random locations. Debian 12, 2 screens, One at 100%, the other at 75% (I think - I don’t seem to be able to open display settings right now)