>>7708039 (OP)
No. The brain doesn't stop developing at a specific age; rather, brain development is a complex, ongoing process that continues into the mid-20s, with some sources suggesting it can extend to the late 20s, 30s or even later than that into adulthood, particularly for the prefrontal cortex, which is crucial for decision-making and impulse control. While the brain reaches about 90-95% of its adult size by age 6, it continues to "rewire" and mature through adolescence and into the mid-20s.
This means you have constant potential to develop new skills and improve on old ones. However, it may feel like progress gradually loses momentum as you continue forward but that doesn't mean your capacity for improvement is stunted. It's more of an illusion brought about by familiarity, aka boredom.
tldr Your brain is always changing and theres no cap on what you can achieve. Keep it up.