The GPG public key is not correct here. Need to install latest GPG public key again.
Please try
# apt-key adv --keyserver pgp.mit.edu --recv-keys 467B942D3A79BD29
It will install correct MySQL-server GPG key on server then add repo of mysql server
For Ubuntu 22.04 (Jammy)
# echo "deb https://repo.mysql.com/apt/ubuntu/ jammy mysql-apt-config
deb https://repo.mysql.com/apt/ubuntu/ jammy mysql-8.0
deb https://repo.mysql.com/apt/ubuntu/ jammy mysql-tools
deb https://repo.mysql.com/apt/ubuntu/ jammy mysql-cluster-8.0
deb-src https://repo.mysql.com/apt/ubuntu/ jammy mysql-8.0" | sudo tee /etc/apt/sources.list.d/mysql-8.0.list
For Ubuntu 20.04 (Focal):
# echo "deb https://repo.mysql.com/apt/ubuntu/ focal mysql-apt-config
deb https://repo.mysql.com/apt/ubuntu/ focal mysql-8.0
deb https://repo.mysql.com/apt/ubuntu/ focal mysql-tools
deb https://repo.mysql.com/apt/ubuntu/ focal mysql-cluster-8.0
deb-src https://repo.mysql.com/apt/ubuntu/ focal mysql-8.0" | sudo tee /etc/apt/sources.list.d/mysql-8.0.list
For Ubuntu 18.04 (Bionic):
# echo "deb https://repo.mysql.com/apt/ubuntu/ bionic mysql-apt-config
deb https://repo.mysql.com/apt/ubuntu/ bionic mysql-8.0
deb https://repo.mysql.com/apt/ubuntu/ bionic mysql-tools
deb https://repo.mysql.com/apt/ubuntu/ bionic mysql-cluster-8.0
deb-src https://repo.mysql.com/apt/ubuntu/ bionic mysql-8.0" | sudo tee /etc/apt/sources.list.d/mysql-8.0.list
For Ubuntu 16.04 (Xenial):
# echo "deb https://repo.mysql.com/apt/ubuntu/ xenial mysql-apt-config
deb https://repo.mysql.com/apt/ubuntu/ xenial mysql-8.0
deb https://repo.mysql.com/apt/ubuntu/ xenial mysql-tools
deb https://repo.mysql.com/apt/ubuntu/ xenial mysql-cluster-8.0
deb-src https://repo.mysql.com/apt/ubuntu/ xenial mysql-8.0" | sudo tee /etc/apt/sources.list.d/mysql-8.0.list
Then run
# apt update
# apt install mysql-server