Something I've been pondering; what does your spirit self appearance depend on, what you looked like at your prime or at your death? Aang still had his 40 year old look, although he would have died over two decades later. Same with Kyoshi and Yanchen; they both look very young, and surely wouldn't have died so young. Roku, however, kept the grandpa look with the long white beard instead of how he looked when he was younger. What exactly determines that?
I think you can depict yourself at whatever age you want so presumably in the prime of your life. Roku I believe was depicted as an elderly man to fit the "wise" role as Aang's advisor. Aang in book 3 despite having hair in the physical world was shown as bald in the spirit world. In other words... Avatar stuff.
я тоже так подумала