Yeah, my first two questions were: "Why don't you get the data from the upstream team's API? Have you discussed this design with them?"

It also happened to me once before--a production system took a dependency on one of my streams in the data lake without my knowledge, and no SLA, then when I made a change to it, they came out of nowhere, blowing me up with e-mails and meeting requests. I told them to go pound sand.