I have all of that too,

http://localhost:3000/login, http://localhost:3000/dashboard, http://localhost:3000/install

but if the "Site URL" is set to

http://example.com

it won't work in localhost.

I think this is an issue with Supabase, I'm also having similar thing happening, open a ticked on GitHub about it or use the feedback widget in the dashboard to report it.

Ok cool, I thought I was doing something wrong at first, but the only workaround I found was swapping out the site url from

example.com

to

localhost

but that would mess up production site.