for non-native speakers: tweenager - a child between the ages of about 10 and 14. (Oxford Languages)

tweenager - a young person between the ages of approximately eight and twelve (Cambridge Dictionary)

seems even dictionaries can't decide on the age

Btw S M L sizes are retarded, why they can't just write normal size like 128 (cm), 134, 152 for cm of height as is commonly used in Europe, my wife regularly checks kid sizes since some teenagers are taller than her. Sadly for adults it's more complicated.

I hate buying pants as adult male since it's complete mess, waist size in Europe in inches, length you never know from where it's actually measured, so if shopping online it's always lottery especially since I am relatively skinny and everything is made either for short or tall fatsos, so if I wanna normal length I end up with huge waist.