A detailed tutorial for installing Skype on Linux Mint 21 or 20 was published by Linux Capable.
How to Install Skype on Linux Mint 21 or 20
Learn how to install Skype on Linux Mint 21 or 20. Step-by-step guide covers downloading GPG key, installing stable or unstable version, updating & removing.
How to Install Skype on Linux Mint 21 or 20 - LinuxCapable