Felix Miata composed on 2023-08-14 02:22 (UTC-0400):

This has been going on too long to remember, probably more than a year now, but at least since 14.0.13. I haven't been able to create a reliable reproduction scenario. Typically, I start a session that has remembered Konsole (at 0,0) with a plain shell tab and an MC tab. With quite some frequency, I wish to copy and paste the first command of the session, and its output, that I have entered in the shell tab, into some text file in MC. The problem is that swiping the mouse from bottom to top to select that output commonly blanks the first Konsole line, which is usually something that produces multiple lines of text output, such as inxi, so that when pasted, the first line of the paste is also blank. The instant case causing me to write this is in Mageia 8/14.1.0, but it IIRC it happens in Debian, Fedora, openSUSE & *buntu also.

FTR, this definitely is happening in Trixie.