Angular 12 Data path “” must NOT have additional properties (styleext)

Try to change

  "schematics": {
    "@schematics/angular:component": {
      "styleext": "scss"
    }
  },

to

  "schematics": {
    "@schematics/angular:component": {
      "style": "scss"
    }
  },

In angular.json. Let me know if this works.