Started with an HR screen.
I passed that, then moved onto the first round of interviews. Some easy C# questions and getting to know everyone. There was some ambiguity as to the in-office requirements for the role.
Interview #3 was the all-day interview, but since I did not have enough PTO for it, they were able to split it up for me into 5 grueling days around my work schedule. Mostly behavioral and high-level questions, including questions about QA and debugging processes. It began and ended with an HR touch-base.
There was poor communication. I was told that C++ was not a primary focus for the role, and that I would not be tested on it. Only to be drilled in C++ in the very next round. No Leetcode-style questions. Mostly language-specific things, bizarrely specific debugging and QA processes, and extremely specific pointer trivia.
I would strongly encourage anyone interviewing to be wary of the technical round. I had to interview with the two most condescending engineers I've ever met. They did not introduce themselves, belittled every accomplishment on my resume, had zero expressions on their faces while doing so, and talked to me like I was a child. While the position looked interesting, I'm glad I was rejected.