I mean it depends entirely on your age lol. when you're 25 you might not want people thinking you're 18 but when you're in your 30s it doesn't feel bad when people think you're early 20s
The only downside is when you have people younger than you thinking you're way younger than them and not taking you seriously in certain scenarios.
"Sometimes you will never know the value of a moment until it becomes a memory."
- Dr Seuss