I don't have a better response for this than that we got a huge flood of candidates for that role, are doing our best to keep up, and have done an imperfect job. We're a small company. You're more than welcome to reach out directly to find out what happened with your application (it's entirely possible that what happened is that the ticket got buried somewhere, and that we'd have been excited to hire you had we not screwed something up on our end).

As for the scope of the challenge: that's deliberate, and we're up front about it. If the challenge is going to take you many hours to complete, and doing that work isn't something that lights you up, then it's the wrong role for you. There are candidates that breeze through it, and there are candidates who wrestle with it for a couple evenings just because they're nerdsniped and enjoy doing that stuff. Both those kinds of candidates are super interesting to us! But we're very comfortable with the idea that the job (in this case: infra engineering) isn't a perfect fit for everybody.