This seems to be issue of some underneath library - see
and
I also see that aspect ratio for Workspace Switcher is wrong.
The positive moment is that Ubuntu MATE 20.04 LTS does not have this problem.
So you can reinstall the 20.04 LTS version if this functionality is essential for you.
Other possible way to fix is to downgrade the WNCK library on 21.10 using the below commands:
cd /tmp
wget -c http://archive.ubuntu.com/ubuntu/pool/main/libw/libwnck3/gir1.2-wnck-3.0_3.36.0-1_amd64.deb
wget -c http://archive.ubuntu.com/ubuntu/pool/main/libw/libwnck3/libwnck-3-0_3.36.0-1_amd64.deb
wget -c http://archive.ubuntu.com/ubuntu/pool/main/libw/libwnck3/libwnck-3-common_3.36.0-1_all.deb
sudo apt-get install ./*wnck*.deb
and then pin these packages by using the following long command:
cat <<EOF | sudo tee /etc/apt/preferences.d/pin-wnck
Package: gir1.2-wnck-3.0
Pin: version 3.36.0-1
Pin-Priority: 1337
Package: libwnck-3-0
Pin: version 3.36.0-1
Pin-Priority: 1337
Package: libwnck-3-common
Pin: version 3.36.0-1
Pin-Priority: 1337
EOF
and then reboot.
To revert the pin use sudo rm /etc/apt/preferences.d/pin-wnck followed by sudo apt-get update && sudo apt-get dist-upgrade.