Form3 interview questions

After two chats with their recruiter, I received the technical test. She stated that my CV is very good and that my experience is enough. At the moment of the interview, I had only one year of experience with Go, over 10 years of programming in other languages. All good until this point, they stated that the test should take me around 4h. They requested me to write a Go client for their accounts API, the mention was to focus on testing the client. All good, I wrote the library, got around 87% coverage, 3 lines of code tests. This took me around two days of work. I was very satisfied with my result. I sent the GitHub repo of the test with a short summary of what I did. At the same time, I also sent my LinkedIn CV, which I haven't previously sent and which the recruiter asked again in a PDF format to send to the devs that will review the test. After a couple of days, I got the message from them that I have been rejected with the summary: "The test was well written. Client creation is simple and methods are easy to use. The tests are clean and easy to read." next to a couple of reasons for rejection like I didn't use a make file, the tests are using mocks and not the DB (who writes unit tests on DB?), an entrypoint.sh file is not present in my docker config file, the account entity doesn't have a builder. For me, these are secondary things, and not the focus of the test. So, what I think happened is that the devs didn't review my CV before the test and they've seen that I have quite a little experience with Go so they found reasons to reject. If this is the case then it's very unprofessional because I lost time with their test. But reading the interview reviews here I find that every rejected dev has a different task to do. I as myself the question, why would you send different tasks as an interview test? I very much assume that they are using this as a pretext to get free development done by devs. A small client here, a small library there. It adds up. I haven't got the chance to have the interview with their dev team to support my decisions taken in the code. I got rejected via an email after working for two days on the interview test. Very bad experience and unprofessional.