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.