Multipart interview which is typical:
1. Recruiter interview
2. Hiring manager interview
3. Technical assignment
4. Technical discussion interview with two team members
5. Potentially a final behavior interview but may be rolled into 4.
For me, #4 was supposed to be a combination that covered discussing the technical assignment solution then diving into other technical, hypothetical, and behavioral questions. A very casual conversation with no follow up questions or in-depth probing by the team interviewing me. I wasn't expecting another interview to follow.
I immediately left the recruiter a brief note following the interview but received no reply back. Two weeks passed and the recruiter never followed up. Typical. I finally reached out and was informed that they changed the title from Staff to Principal and hired someone else. Nice.
It's unfortunate that people and companies behave this way but is also why burnout is so high among software engineers. These interviews take a lot of time and the least a company could do is follow up at the end.
The entire process took about six weeks.