Ubuntu Desktop 21.10 freezes when interacting with GUI (desktop environment) on Raspberry Pi 400

I confirm the same issue (random hangs in GUI after clicking) is happening for me too. I have tested Ubuntu Desktop 21.10 both on a Raspberry Pi 4 (4Gb), a Raspberry Pi 4 (8Gb) and the Raspberry Pi 400 (4Gb) all booted from SDCards (SanDisk Ultra 16Gb or 64Gb), USB Stick (SanDisk Extreme Pro 128Gb) or from external USB 3.0 to SSD adapter (with 1Tb Samsung EVO 860 SSD inside). I'm using the latest firmware and the original power supply.

If I can help with more testing to isolate and maybe fix the problem please let me know.

Hope this gets fixed soon as I'm really looking forward to use this release.

***Update 1:

I downloaded and wrote UBUNTU-21.20-PREINSTALLED-SERVER-ARM64-RASPI image to a Corsair GTX (128Gb) USB Stick.

As there is no desktop environment by default in the server edition I ran the following commands to install it:

apt update && apt dist-upgrade -y && apt install ubuntu-desktop -y

I rebooted the system and I now have a perfectly working desktop environment. System About displays the following:

OS Name: Ubuntu 21.10 | OS Type: 64-bit | GNOME Version: 40.4.0 | Windowing System: X11

To my surprise it doesn't freeze anymore so I'm not sure what causes the problems in the default Ubuntu 21.10 Desktop release but I suspect it's not GNOME 40.

I'm open for more suggestions as to what else can I test/try.

*** Update 2:

According to this site: a temporary fix would be changing in /boot/firmware/config.txt

the following line:

dtoverlay=vc4-kms-v3d

to:

dtoverlay=vc4-fkms-v3d