[Question] How to disable the statusline-alike line above the command output?

When command output uses two lines or more, there is a horizontal line above the command output. This is not the statusline as ‘set laststatus=0’ does not disable this line. What is this line called and how to disable it? Vim does not have this line. Any help would be appreciated.

set laststatus=0
set display-=msgsep