sudo apt update
sudo apt -y remove apt-listchanges
sudo apt -y upgrade
sudo apt -y full-upgrade
sudo apt -y autoremove
sudo sed -i 's/buster/bullseye/g' /etc/apt/sources.list
sudo sed -i 's/buster/bullseye/g' /etc/apt/sources.list.d/*.list
sudo sed -i 's#/debian-security bullseye/updates# bullseye-security#g' /etc/apt/sources.list
export LC_ALL=C 
sudo apt update
sudo apt -y upgrade
sudo apt -y full-upgrade
sudo apt -y autoremove

References: https://linuxize.com/post/how-to-upgrade-debian-10-to-debian-11/