When using Codespaces in your browser, you’ll need to add this CORS policy:
allowed-origin-patterns: 'https?://*.githubpreview.dev‘
Find an example of how to change that in my generated jHipster application:
solve CORS error · SandraAhlgrimm/jhipster-sample-devcontainer@e0191f6 (github.com)

And to make sure, you won’t have to do that in your next generated project, we added this to the jHipster generator. https://github.com/jhipster/generator-jhipster/pull/17683