Giving back would be getting involved in social causes, solving problems for free with no expectation of any return, and in this context giving back to the open source community. Stripe is awesome but in this context it would be great to hear about how they are supporting open source projects they are built on than how they are solving problems in payment processing.
Open source funding is a bit of a mess at the moment. There is a huge lacuna on how to highlight startup companies (and thus encourage others) that are successfully built on open source contribute back. Companies that use open source should at least have a page listing the projects they are using and how they are giving back. There is no visibility or any initiative that tracks and encourages this positively. Without focus and organization nothing happens. Another important thing is giving back should be simple funding for open source projects and not hiring the developers or adding developers. That seems to be more about gaining influence than supporting the project for everyone.
The more worrying thing is a general lacuna of user representation in open source in an organized fashion, developer funding of popular and interesting projects that are not a part of the startup scene and just general funding. The inevitable result is open source will if it's not already, be hijacked by corporate interests. Ultimately money makes its own agenda, and if users do not secure their interests others will.