gdm conffile prompt during bionic to focal upgrade

Doing some test upgrade, doing a new bionic install (autologin enabled from the installer) and upgrading, switching to focal directly without using it, the upgrade displays that config file change prompt

--- /etc/gdm3/custom.conf 2020-04-21 17:30:22.379041984 +0200
+++ /etc/gdm3/custom.conf.dpkg-new 2019-10-07 18:23:07.000000000 +0200
@@ -3,13 +3,12 @@
 # See /usr/share/gdm/gdm.schemas for a list of available options.

 [daemon]
-AutomaticLoginEnable=true
-AutomaticLogin=ubuntu
-
-# Uncoment the line below to force the login screen to use Xorg
+# Uncomment the line below to force the login screen to use Xorg
 #WaylandEnable=false

 # Enabling automatic login
+# AutomaticLoginEnable = true
+# AutomaticLogin = user1

 # Enabling timed login
 # TimedLoginEnable = true