Cannot publish npm package (E403: forbidden)

I am trying to publish an unscoped public package on npm.

I logged in through command line and launched npm publish from dist folder. Anyway, I always get this error:

npm ERR! code E403
npm ERR! 403 403 Forbidden - PUT https://registry.npmjs.org/flexing - Forbidden
npm ERR! 403 In most cases, you or one of your dependencies are requesting
npm ERR! 403 a package version that is forbidden by your security policy

this is my package.json file

{
  "name": "flexing",
  "version": "0.0.1",
  "author": "Igino Boffa",
  "peerDependencies": {
    "@angular/common": "^10.1.6",
    "@angular/core": "^10.1.6",
    "chroma.ts": "^1.0.9",
    "font-awesome": "^4.7.0",
    "golden-layout": "^1.5.9",
    "jquery": "^3.5.1",
    "tslib": "^2.0.0"
  },
  "scripts": {
    "build": "ng build --prod && npm run bundle-styles",
    "publish": "cd ../../dist/flexing && npm publish",
    "build-publish": "npm run build && npm run publish",
    "bundle-styles": "scss-bundle -c scss-bundle.config.json"
  },
  "repository": {
    "type": "git",
    "url": "https://github.com/iboffa/flexing.git"
  },
  "devDependencies": {
    "@types/jquery": "^3.5.4"
  },
  "description": "Angular flexible layout library",
  "main": "karma.conf.js",
  "license": "ISC",
  "keywords": []
}