This is something that actually drives me a way from using "a thing" - that some team post something "open source" - but in reality it's a product and there's a pricing tab on the website.

I think we've overloaded the term for sure. I'd prefer honesty - "hey we have a new product/service/platform! We've opened up our customer tooling source code and made it free and available for anyone to contribute too"

To me releasing open-source to specifically try get people to sign up to a paid product is a sales tool.

It is harder and harder to publish SaaS building bricks as open-source, as too many companies are not contributing back their change (sometimes called "freeriders"), leading to the core developers abandoning open-source to protect their business model. This post is a summary of the discussions that happened between Garage core developers and their strategy to make sure that everyone share their improvements while making legally mandatory that future versions are published under the same open license.