

Which study are you talking about? This is the mainstream view of neuroscientists.
Here’s what I got from MentalHealthDaily (sources at the bottom of the article):
Neuroscientists largely agree that the human brain hasn’t fully developed until (at least) the mid-20s.
It may seem logical that those aged 18 to 25 are completely mature, the brain still is maturing – specifically the area known as the “prefrontal cortex.” Changes occurring between ages 18 and 25 are essentially a continued process of brain development that started during puberty. When you’re 18, you’re roughly halfway through the entire stage of development. The prefrontal cortex doesn’t have nearly the functional capacity at age 18 as it does at 25.
This means that some people may have major struggles with impulsive decisions and planning behavior to reach a goal. The brain’s reward system tends to reach a high level of activation during puberty, then gradually drifts back to normal activation when a person reaches roughly the age of 25. Adults over the age of 25 tend to feel less sensitive to the influence of peer pressure and have a much easier time handling it.
Okay, I’ve got the consensus of neuroscientists on the one side, and then I’ve got a rando on Lemmy who can’t even cite a study on the other. You gotta give me more to go on here.
Also, they aren’t saying that the brain stops changing at 25; they’re saying that it’s mature at 25. These are two different things. The rest of your body changes as you get older, so it would make sense that your brain does, too.
The important part is the prefrontal cortex isn’t fully developed until your mid-20s. That’s why you make a lot of rash and stupid decisions when you’re 18-25.