literally everything. taste in music, what you watch, the things you eat, the things you find visually pleasing. but most importantly mentally. you change how you see other people, how you see yourself. what you look forward to in life, what you look forward to in other people. you change pretty much all around. none of these changes will click instantly but you definitely will just on a random day realize you have changed. your perception on the world will grow and as a result, it changes.
i may not speak for everyone here but as a result of this change (which is caused by your mind literally growing), your sense of child-like wonder kind of vanishes with it. i dont play video games nearly as much as i used to. if i do its 100% of the time a game i already played a long time ago. its like trying to chase that familiar child-like wonder again that you felt as a kid or a teenager because you cant get it naturally anymore. it started happening around your age too. so yeah, expect that to happen :P