What is this functionality of emacs/Doom/evil/cider of keeping prompting "Lisp expression:" when typing in evil input mode?

@Carsten_Behring and @mjmeintjes are you using emacs-doom (maybe lispyville.el) with lispy.el?
I’m trying to find the corresponding source code for the behavior of keep prompting “Lisp expression:”.

I did find a few places of (read-string…) function call, that might be the source in lispy.el.
but I found none of read-string in lispyville.el

I also check (interactive “p”…) in both modules, and found none plausible.