I upgraded to Emacs 27 recently, and I found two little annoying things: there’s now a warning about the
cl package that has been deprecrated for a long time now (everything is okay in Doom core modules, this is just the packages
persp-mode which happen to trigger the warning with their
(require 'cl)), and Ivy posframe gets sometimes stuck. I encountered some freezing issues as well, but this may well be due to the
with-no-titlebar option in the HEAD version of emacs-plus.