Possibly. But it can be significantly improved with strength training and good nutrition.It's not clearly wrong. It's a medical fact."Boys tend to show the first physical changes of puberty between the ages of 10 and 16. They tend to grow most quickly between ages 12 and 15. The growth spurt of boys is, on average, about 2 years later than that of girls. By age 16, most boys have stopped growing, but their muscles will continue to develop."https://kidshealth.org/en/parents/growth-13-to-18.html#:~:text=Changes%20in%20Boys&text=They%20tend%20to%20grow%20most,muscles%20will%20continue%20to%20develop.I didn't say ALL boys stop growing at 16.Most resources say 16. Some say 16-18.Most boys are NOT still growing into their 20s.Everybody has anecdotes about somebody they know that grew 4 inches in university. Those are mostly exaggerated, and/or outliers.Your anecdotes about your friends getting taller doesn't change what happens for "most" boys.
I already take calcium/vitD combination tablets since my anti hormonal treatment started and got worse despite it. I asked my oncologist about vitamin K and she waved it off saying she had never heard of it. So I'd have to look into evidence for that if I want to have mine measured and supplemented I think. Hadn't heard about the combination with vitamine C either. Here they're just like 'oh the calcium and vitamin D don't do enough? Well guess we'll bombard with bisfosfonates then'