When you have several credentials for different applications on 2nd level domain (e.g. app1.test.com, app2.test.com etc.) the first match will be chosen.
It’d be great to see auto-filled the one that matches the most and not just random one.
It would be available for the next upcoming release based on this GitHub’s issue: https://github.com/bitwarden/browser/issues/77
This is done for next release with the URI match options. See https://github.com/bitwarden/browser/issues/771