Checkbox (Australia) Senior Software Engineer interview questions

Ended up having no feedback after 3rd round. Waste of my time. 1st round with one of the founders to go through the general HR questions. 2nd round with a take home code challenge to complete a fullstack project with both FE and BE required. I took 2 days to ensure it's well polished and get all the `nice to have` features delivered as well. It came back with quite quick follow up with 3rd round. There were 2 engineers interviewing me, with all questions trying to drill down deep into the tech details and system design. I suppose I answered most of them with quite confident answers. Then I got ghosted without any feedback for 3 weeks, I suppose it's a NO but I could never tell as I did not hear anything back from them afterwards.