Enter a multi-line command in the REPL. Press Enter and then Ctrl-Up to get the input back, with the cursor being at the very end of input. Now press Ctrl-A. Instead of moving to the beginning of the last line of the multi-line input, the cursor moves to the beginning of the first line. This happens for all Julia versions from (at least) 1.10 to master.

I've confirmed that in the function move_line_start somehow the branch

is triggered although Ctrl-A is only pressed once. (While not being documented, pressing Ctrl-A twice brings you to the beginning of the input.)