Builder app can't connect to localhost:3000


I’ve created a new NextJS app and integrated builder as described in the Automated Integration guide. However when I open the /builder-demo page in the application I get an error saying that Builder can’t connect to http://localhost:3000/builder-demo

When I deploy the page to Vercel, app works without problems. What may be causing app not being able to connect to the dev server running on localhost?

I use NodeJS v18.19.1.

Seems like it was problem with my web browser. It doesn’t work in Brave, but it works in Firefox.