Meta Software Engineer New Grad interview questions

I applied in October with referral. I was reached out by the recruiter within 2 weeks. We scheduled a first interview, algo. I got feedback within 2 days, scheduled onsite interviews: 2 algo and one with manager. I solved all of the problems, but sometimes had small issues with corner cases. Interview with manager was mostly about behavioural questions you get also in other companies - but this time interviewer was very inquisitive, wasn't satisfied with very general answers, but wanted to know my real motives. Everyone was super friendly and humanly. The downside is, you cannot negotiate a grad offer, which really surprised me - I thought it wasn't the case until very recently.