Kali Linux 2020.4 was released yesterday by Offensive Security, and it takes the big step of changing the default shell from Bash to ZSH. The new default shell is now ZSH for users who install the distribution. New Bash theme also includes a makeover for the Bash shell to use a similar-looking theme to the Kali’s ZSH shell. This version will display a dynamic message (MOTD) on login that offers suggestions on fixing detected issues with the installation of Kali Linux.
Source: https://www.bleepingcomputer.com/news/linux/kali-linux-20204-switches-the-default-shell-from-bash-to-zsh/