Looks like I'm adding to the chorus here, which I should have checked beforehand. I applied on February 21, and on March 3 I got an email from Fetch saying I had been "hand selected" to complete a code exercise. I went well beyond what the exercise prompt requested, submitted it on March 5. I emailed the recruiter that day and on March 15, never heard back from them. On March 19, I got the automated Greenhouse rejection, no feedback, never heard from a human.
This is truly bad form. Looks like they're just farming for free code. I would never work for this company.