I definitely would never call GitLab Open Source. I can't comment as much on the others. Sidekiq is actually how I think the world should work: its open source, and then they sell Sidekiq Pro. One is Open Source, one isnt. The issue is most people don't operate that way.
GitLab Community Edition is Open Source, GitLab is not. Cal.com isn't open source, but is the Cal product? I'm not sure. Given I started Sentry I can at least use it as an analogy. Early days Sentry was open source, but getsentry.com was not (which was our billing infra). No one would have called Sentry Open Core, because no part of "Sentry" was closed source. That's not true for most Open Core.