Stuck in tty1 after updating

What Happened?

The lightdm greeter does not launch when rebooting the OS after an update.

Steps to Reproduce

Run sudo apt update && sudo apt upgrade in Terminal.
The OS notifies to restart after the update is finished.
Restart the OS.
After restart, lightdm does not launch and a tty appears with this text: elementary OS Jolnir elementary tty1 elementary login:

Expected Behavior

I expected lightdm to start when the OS starts to greet the user with a graphical login instead of a tty prompt.

OS Version

6.x (Odin)

Software Version

Latest release (I have run all updates)

Log Output

$ ps aux | grep lightdm
root    930 0.0 0.0 305852 7040 ?      Ssl  17:22  0:00 /usr/sbin/lightdm
# my ps aux command showed up here as well.

$ startx
X.Org X Server 1.20.13
X Protocol Version 11, Revision 0
# attempts to start, but gives this message after crashing:
xinit: connection to X server lost

$ cat /var/log/Xorg.0.log | grep nvidia
# no output here
$ cat /var/log/Xorg.0.log | grep nouveau
[   1451.666] (==) Matched nouveau as autoconfigured driver 0
[   1451.666] (II) LoadModule: "nouveau"
[   1451.669] (II) Loading /usr/lib/xorg/modules/drivers/nouveau_drv.so
[   1451.671] (II) Module nouveau: vendor="X.Org Foundation"

Hardware Info

AMD Athlon X4 860K NVIDIA GTX 960 2GB 8GB DDR3 RAM I installed nvidia-driver-515 via apt and was using that prior to the update. startx also does not work as listed above in the Log Output. Based on the info from the /var/log/Xorg.0.log file, it appears to be attempting to use the nouveau driver now. I tried running sudo ubuntu-drivers autoinstall, but that did not install or change any packages.

elementary / triage