Tech bro uniform is the stereotypical Silicon Valley male wardrobe: Patagonia vest, jeans, sneakers, AirPods. Often used mockingly. Not concerning, just industry vocabulary. If your kid uses it constantly, ask them where they first heard it, not to police their speech but to understand which online community they are in. Most slang of this kind moves through TikTok and group chats, so seeing it in your child's vocabulary just means they are plugged into normal teen internet culture.