This entire process took nearly 7 weeks from first contact to final rejection. Read on...
4 days from application to first contact.
First round interview was with directory of infrastructure 6 days after that.
Second round was with two of the engineers on the team 4 days after round 1. This went extremely well. However, one of the engineers came off as a bit smug, and threw up some red flags for me. The other was a pleasure to talk to, however.
Next step was the take-home project, which I received shortly thereafter.
The project was super vague. The technical requirements were mostly clear, but exactly what was expected, how much time was allowed, how in depth I was supposed to go, what tools we could use, were all unclear. I was invited to a private slack channel with the other team members in order to... ask questions? It wasn't clear what the team part of it was supposed to be like. Was I allowed to ask for help and turn it into a collaborative effort?
I took a week to finish the project, working in the evenings. Whenever I had questions, it would sometimes take a day to get a response, but part of that may have been the timezone difference. Again, it was never clear how long the project was supposed to take. I also wasn't paid for my time, as others have noted.
In the end, I was told my resume would be kept on hand for future open positions. I don't know if this was stated as a courtesy or not, but I was never contacted after that.