Firebase CLI v7.0.0 is incompatible with Node.js v6.17.1 Please upgrade Node.js to version >= 8.0.0

Problem:

Firebase CLI v11.0.0 is incompatible with Node.js v14.17.5
Please upgrade Node.js to version >= 14.18.0
just install,

1. "npm install -g firebase-tools@10.9.2"
2. "firebase init"
3. "firebase deploy" and it's solved.

With version 7.0.0, the Firebase CLI dropped support for node 6. You will need to upgrade your local node version to at least version 8. (8.0.0 actually has bugs - you should use something more modern.)

Personally, I recommend using nvm to install and run node, as it's easy to install and upgrade, and doesn't require root access to change system packages.

You can simply uninstall your node js from your pc and download current latest version of node js from https://nodejs.org/en/download/current and than install it.