They have published a bunch of stuff about their internal tools in the past. Look up https://stripe.com/blog/stripe-home and compare it to this, as an example.
It's always possible that in reality they were always a bit less polished behind the scenes though.
Its always more likely the company pushing the PR is less polished than they present themselves.
It's possibly a cost benefit thing. Moving quickly with AI leaves blood splatter, but if you get enough in return you decide it's worth it anyway.