Just for future readers.
The version of Node.js on your device has a direct impact on what Node-Sass you must use.
Here’s a link: node-sass - npm
To find the version of Node you’ve installed, type this in a terminal:
node -v
Knowing your version, look that up in the link I shared.
For example, my laptop is running Node v14.15.4. So I need Node-Sass 4.14+.
But some of my cloud VPS are using much-newer versions of Node, like v16. So they need Node-Sass 6.0+.
When you install Frappe framework, the 'package.json' and 'yarn.lock' files are provided for you. The Node-Sass specified inside those files may not be what you need, for your device.
In which case, manually install the correct Node-Sass using yarn.