utrechtsouth
No it's the government.
Also keep in mind that the legal options and PR options are tightly coupled. Regardless of the outcome of any legal option (e.g. "JO anmälan"), the PR generated around it may itself lead to a change if it gets enough attention (e.g., Anna König Jerlmyr seems to be in charge of Stockholm municipality at the moment). Make it easy for them to get good PR and make it clear the other option is to get bad PR.
These questions are larger than this project. This is about how the government itself builds API:s. That's big.
So that leaves a defense against... their own users? Makes no sense.
Plus the tax payers funded the platform so it's not like the government has any legitimate interest in protecting the product itself like a private business might.
Trial and error using a free market place.
While there is a technical issue here, there is also a legal issue and a PR issue.
Government institutions have a duty of care and a duty to help to private individuals. Since they are apparently working _against_ people in this case, they are probably in breach of the law.
Description of relevant rules here (in Swedish). https://www.mfd.se/verktyg/lagar-och-regler-om-tillganglighe...
I strongly suggest that you file a formal complaint against the government agency. This is easy to do and you can do it here. https://www.jo.se/sv/JO-anmalan/
When you have filed the complaint: MAKE IT PUBLIC (hacker news follow up story, twitter, linkedin, etc). This is because there is a political dimension to this issue and if there is anything politicians care about, it's jobs (their own).
Good luck and keep us updated! I'm sure lots of people will be happy to spread a copy of the complaint around.