I had a similar experience adding new functionality to a web application. It was a simple enough feature that I was able to supply the English myself, but I knew enough not to provide the international copy, even though the only other language we supported was a language I studied in school. I asked the product manager a few times, then created a ticket assigned to them and sent them the link. Meanwhile, my code got reviewed and deployed, behind a feature flag of course.
As soon as they found out the code was deployed, the product manager asked if we could turn on the feature. I reminded them that the reason we supported the other language was that it was a legal requirement for our customers in a certain country. They said turn in on, nobody was going to notice except a big US customer who desperately needed it. So I did.
Within a few hours we had an enraged customer on the phone. Credit to the product manager, they took full responsibility, but the initial response from the founder/head of customer success who took the call was to walk straight to my desk and ask me what the hell I did.