The whole "25 y/o brain fully developed" thing is not something you should be putting much weight in, for what it's worth. https://slate.com/technology/2022/11/brain-development-25-year-old-mature-myth.html
I think you might be missing the point of the article. I didn’t use a specific number because people are all different and develop differently. It’s generally around the mid to late 20s that most humans brains are fully developed.