Dell 8K (UP3218K) dual DP cable tiling not working correctly with 3.38
After updating to Gnome 3.38 (in Debian Testing) my display's tiling is not handled correctly. This display utilizes a pair of DisplayPort cables to tile both 3840x4320 halves into a single 7680x4320 display. I can configure both halves under 3.38 but Gnome treats them a two separate displays with the menu bar covering only half of the screen. Gnome 3.36 (Debian Testing) and 3.30 (Debian Buster) worked out of the box, with no special settings needed. Prior to Gnome 3.38 the Displays setting panel would only show a single 32-inch 8K display and the tiling was only exposed via xrandr or nvidia-settings, under Gnome 3.38 the Displays setting panel shows both halves of the display. Reverting to Gnome 3.36 causes the display to work as normal with no special configuration needed.
Kernel version: 5.9.1-1 nvidia-dkms version: 450.80.02 Display: Dell UP3218K Video Card: Nvidia Quadro GV100
Packages I've reverted, which cause this to work correctly again, are listed below. I'm not sure which specific 3.38 package is responsible as many of these are dependencies.
gdm3_3.36.3-1_amd64.deb
gir1.2-gdm-1.0_3.36.3-1_amd64.deb
gir1.2-mutter-6_3.36.6-1_amd64.deb
gnome-control-center_3.36.4-1_amd64.deb
gnome-control-center-data_3.36.4-1_all.deb
gnome-core_3.30+3_amd64.deb
gnome-session_3.36.0-2_all.deb
gnome-session-bin_3.36.0-2+b1_amd64.deb
gnome-session-common_3.36.0-2_all.deb
gnome-settings-daemon_3.36.1-1_amd64.deb
gnome-settings-daemon-common_3.36.1-1_all.deb
gnome-shell_3.36.6-1_amd64.deb
gnome-shell-common_3.36.6-1_all.deb
gnome-shell-extension-desktop-icons_20.04.0-3_all.deb
gnome-shell-extension-prefs_3.36.6-1_amd64.deb
gnome-shell-extensions_3.36.2-1_all.deb
libgdm1_3.36.3-1_amd64.deb
libmutter-6-0_3.36.6-1_amd64.deb
mutter_3.36.6-1_amd64.deb