level: 2-2 (senior fullstack)

Codings (pass): 2 mediums high freq. nothing tricky or special. Interviewer is from SG office. Very nice person. English has strong accent, but very fluent. No communication issue.

SD (pass): Design Tiktok. Nothing special, mostly knowledge tested from the system design books you read. Interviewer is in the US and the HM for the position. English - native fluency. I had great conversation after finishing the design. Very nice, technical, and answered a few questions I have.

Skip level manager: This is where things went from very nice to WTF!!! Manager from China, doesn't speak English. First 20 minutes asking gossip questions about life in the US and totally unrelated topics to the interview. Then asked me to mention a project I did. I gave an example in the STAR method like most of the candidates in the US are trained to do. I kept it concise and asked to dive in. Then he said your solution was not improving the absolute performance. It wouldn't solve the problem. I said well, there was more issues at the company than just milisecond level performance. No one knew how to optimize the legacy system, blocking I/O, and a couple of other points. Then the interviewer abruptly ended the interview and said "the interview is over". So, less than 10 minutes of bq, and he just flagged me with one thing I did that he thinks was wrong...

Overall, I understand if a team has a desired type of candidate or required knowledge with prior experience. However, putting the candidate through the full loop, and then shut you down like you are just a expendable "tool" after all that is just eye opening and TBH, unprofessional.
HM seems like has no power in terms of choosing their hires. It's most likely the Chinese senior managers are making the call.

I really hope I was just the unlucky one with a promising company. But after searching around, I have found similar experience. As a suggestion to anyone who is not desperately wanting to join them, please be aware of the potential red flags.