Login succeeds on Docker Hub and Docker Desktop (Windows) but fails with Docker on Linux

User: flyway

On Windows, Docker Desktop (Docker CE 18.09.2) uses https://index.docker.io/v1/ and the docker login command succeeds
On hub dot docker dot com the same credentials are also accepted.

Yet on Ubuntu (Docker CE 18.09.6), the exact same docker login command fails with Error response from daemon: Get https://registry-1.docker.io/v2/: unauthorized: incorrect username or password

What am I missing??