I am observing a strange behavior in evil-mode that I'm unable to figure out what is causing it: In insert-state, pressing "M" does not insert a capital m as expected, but instead gives me the following prompt in the minibuffer (see screenshot 1 below). Strangely, "M" works in visual-state and normal-mode. I have double checked my init.el and I have not accidentally bound M to anything, and all other letters seem to work.
What kind of mode is this showing and how can I debug this?
Update: Turns out this line was the culprit:
(define-key evil-insert-state-map "M-r" 'evil-paste-from-register)
Is this a bug in evil-mode?