Toggle off the "press up to copy last message" feature?

I figure there’d be a way to toggle this off, but I can’t find one.

It’s incredibly annoying when I type something that is longer than 1 line, see a typo above, hit up on the arrow instinctively, and now my message is gone. Sure, I can hit down to get it back but now I have to stop what I’m doing to move the mouse to the typo to fix it. At the very least, it should only copy the previous message when you hit up on the TOP line.