npm WARN deprecated core-js@2.6.11: core-js@<3 is no longer maintained and not recommended for usage due to the number of issues

Indeed the issue was with cache. npm clean-install worked.

Try:

npm cache clean --forcenpm install -g @angular/cli@latest

angular npm-install core-js

It's a npm cache problem. Go to the path:

and delete its content. Then open your console in administrator mode and execute the npm install command again

CodeHunter