It's not a subculture, no one identifies as chavs. The so called uniform is just the uniform of a white working class estate which is why the term chav became quickly frowned upon because it's essentially a sneery shorthand for a white working class lad or man. Have not noticed any difference between lads who dress in tracksuits vs lads who dress in a T shirt or jeans. It's kind of like going to an American suburb, seeing all the lads in a T shirt and shorts, and saying it's a subculture when it's just the standard way lads dress. I've had people online almost unanimously call me a chav just from my description of what I wear.
For context, am a forty year old man. I wear a chain necklace, cap, trackie, and 95s. Most of my mates dress like this, many of which I've known since secondary school and easily the most loyal mates too. They're in their thirties and forties with jobs, children etc. If you think most arseholes you meet are lads in tracksuits, it's probably because most lads in your area are wearing them. I have not noticed any difference in how men in tracksuits act compared to men in tees and jeans.
I haven't heard the word chav being uttered from anyone's mouth in over fifteen years but on Reddit I've seen it being used dozens upon dozens of times often without knowing the character of the person even.