For me, it was time management and working with a team/communication. Until I started working with others, I kept to myself doing my own things. Once I started working with people, I had to adjust how I work, brush up on communication skills, and most importantly time management. This took a while, and I'm still not the best at it, but you need those skills in order to succeed as a dev. When you don't have those skills, you end up causing problems for everyone, and nobody likes that 🤔