ServiceTitan interview questions

Approached by a serviceTitan recruiter in LinkedIn. R1: 30 mins phone interview with a lead recruiter. R2: Hackerrank coding challenge(75mins). It was good. Easy problem. R3: Pair programming session with Senior Manager(1.5 hours). Asked to design a Collection type. Difficulty type: Average R4: Pair programming session with a Manager(1.5 hours). Problem was related to asynchronous programming with concurrecy level. It was average..solved it on time and then interviewer asked me to write the unit tests..no unit test frameworks are supported by the hackerrank. So I asked his expectations and the interviewer told me to test manually and he said, if he understands my test then its good. I wrote the tests and it passed..then he asked me to write a test to test the concurrency level..first I was stuck then few minutes later I proposed a POC..I also told him that I knew its a bad way to test but its just for testing, if the POC works then I will fix my tests. Fortunately POC works..then seems like he was happy..then he suggested me a different way to test that..it was a hint. I discussed with him about that approach he proposed and finally wrote the test as he wants..and it passed. We both were happy..then he talked with me 5 mins about the size of their teams and the tech stack they use. I thought it went well. But 4 days later, they sent me an email that I didn't pass the coding round.. nothing to say..waste of time..I think their recruiters might need to fix up some interview arrangements in each month, otherwise they will be out of work.