Mysql works flawlessly. But, these packets which have been kept back have messed up with apt package manager.

The following packages have been kept back:  

mysql-client mysql-server 0 upgraded, 0 newly installed, 0 to remove and 2 not upgraded.

Mysql "apt-cache policy mysql-client mysql-server" as requested by @popey

apt-cache policy mysql-client mysql-server                   

mysql-client:

  Installed: 8.0.21-1ubuntu20.04

  Candidate: 8.0.22-0ubuntu0.20.10.2

  Version table:

     8.0.22-0ubuntu0.20.10.2 500

        500 http://archive.ubuntu.com/ubuntu groovy-updates/main amd64 Packages

        500 http://archive.ubuntu.com/ubuntu groovy-updates/main i386 Packages

        500 http://archive.ubuntu.com/ubuntu groovy-security/main amd64 Packages

        500 http://archive.ubuntu.com/ubuntu groovy-security/main i386 Packages

 *** 8.0.21-1ubuntu20.04 100

        100 /var/lib/dpkg/status

     8.0.21-1 500

        500 http://archive.ubuntu.com/ubuntu groovy/main amd64 Packages

        500 http://archive.ubuntu.com/ubuntu groovy/main i386 Packages

mysql-server:

  Installed: 8.0.21-1ubuntu20.04

  Candidate: 8.0.22-0ubuntu0.20.10.2

  Version table:

     8.0.22-0ubuntu0.20.10.2 500

        500 http://archive.ubuntu.com/ubuntu groovy-updates/main amd64 Packages

        500 http://archive.ubuntu.com/ubuntu groovy-updates/main i386 Packages

        500 http://archive.ubuntu.com/ubuntu groovy-security/main amd64 Packages

        500 http://archive.ubuntu.com/ubuntu groovy-security/main i386 Packages

 *** 8.0.21-1ubuntu20.04 100

        100 /var/lib/dpkg/status

     8.0.21-1 500

        500 http://archive.ubuntu.com/ubuntu groovy/main amd64 Packages

        500 http://archive.ubuntu.com/ubuntu groovy/main i386 Packages