I highly recommend this video (which another very kind member shared a little while ago) which may help with your question.
The thing about weight loss is there is a lot of averages & the stats you mentioned are an example. There are averages for how much weight you’ll lose, how long it will take, how fast or slow you’ll lose, etc. They’re averages because there are so many factors which influence those stats: age, gender, starting weight, weight loss before surgery, weight loss & gain history, health issues, medications, your new set point, how closely you follow your plan, the lifestyle changes you implement (food choices, activity, …) & so on. As with all averages some will exceed them others won’t reach them. What averages give you are an idea of what might happen. Not a rule but a guideline of what might happen.
I’m one of those who exceeded the average. At 12 weeks from surgery I’d lost about 15kg. I’d lost 31kg (including the 5kg pre surgery so about the double amount & got me to my goal) at 6 months. At 12 months I’d lost a total of about 41kgs (not intentionally but it was where my body wanted to be - my new set point). I bounced around there for another couple of months before settling about another kilo lighter (total 42.5kg lost). This was my experience.