Apparently caused by this patch:

commit 5761a1a3939e23d8e8c725241dd9398a12f191b0
 Author: João Távora <joaotavora@gmail.com>
 Date:   2019-11-08 00:11:34 +0000

     Nudge icomplete-mode a little closer to fido-mode

     * lisp/icomplete.el (icomplete-completions): Don't use ellipsis when
     truncating determ in fido-mode.  Highlight the center part of
     determ with icomplete-first-match.