I actually interviewed for several Software Developer jobs at Unity in a span of around 6 months so your mileage may vary.
Every process started with a screen call with a hiring recruiter where they fill you in on Unity's values, detail the job responsibilities, and they'll also ask about your previous experience to gauge whether you'd be a good fit or not.
After this step, I was either asked to chat with the hiring manager for the role, or given a take-home assignment. The hiring manager will ask relevant questions on your experience and learn more about you.
Should this go well, a more technical interview is usually scheduled where you'll do a coding exercise along with the interviewer. I really appreciate when every company does this instead of the online timed exercises. Every technical interview I had, I felt like the focus was on how I attempted the problem, and not the problem itself.
The last step after this is meeting with a short panel of interviewers. They will ask technical questions as well as determine whether you are a culture fit. For the position I was accepted for, the whole process was completed in a month.