Stripe appear to have been building this for quite a long time. I remember seeing bits of this in the API back in ~2018, and it may have been there significantly longer.

I think in general they experiment with building lots of connections that most customers never see. At my previous place of work we integrated Klarna with Stripe, I see this has also now launched, but we used it in private beta for a long time.

While it's nice that this is now available, I wonder how well it works in practice. We had numerous problems with our Klarna integration – mismatches in expected flows between Stripe/Klarna, needing to use some Klarna APIs directly and some via Stripe, and neither Stripe support nor Klarna support having any idea how the integration worked.