Discord Software Engineer interview questions

Recruiter screen, technical screen, virtual onsite with 4 rounds (two technical, 2 behavioral). Overall experience was good, recruiters were kind and had a quick turnaround for updates. They even gave a doordash gift card for interviewing with them,

Recruiter call. Usual behavioral questions, except I got blindsided by a "tell me about a time when you were building something and had to make tradeoffs". Apparently my answer for that was good enough since I moved on, but prepare for things like this. I wasn't because I wasn't applying for Senior, but I digress. Oh yeah, and the recruiter was like 6 minutes late. Coding test. It was the chat server question. I was able to solve the first part of the question, and got through the next part as well. I communicated with the interviewer throughout, outlining my thought process, and testing the functionality throughout. I then had a nice chat with them about Discord and what it's like to work there. Unfortunately, it amounted to nothing because I got a rejection email in 3 days. I mean I solved their question and even got the "extra" part, I don't know what else they wanted. Also, something to keep in mind. The interviewers' emails seem exceptionally supportive, but when I sent emails to ask some questions before the interviews (as they themselves seem to encourage), they went ignored. So, that bit feels entirely disingenuous.