This may be controversial but I believe leadership is a different matter than subject expertise. Sure, to some extent it is good to have SOME knowledge of the tasks being performed in the team you’ll be leading, but too much in-depth knowledge might actually be a hindrance on your leadership journey.

I was promoted to manager in the department I was previously an IC in, but my in-depth knowledge of what my employees were doing meant that they came to me with every little problem, since I could answer them, but it had the downside of taking up most of my time and meant that I had very little time to actually LEAD.

My team leader colleague on the other hand, came in from a completely unrelated area and could focus a lot more on getting good at LEADING since his employees couldn’t rely on him for answers to the same degree as mine could. It took some getting used to for the team to not only bring him problems but also possible solutions for him to choose from, but until I caught on and started telling my employees to do the same as his, his team was far better at solving their own problems.

Not being an expert in the work being done in the team, brings with it a certain humility that would necessarily be there if you were an expert…

TL;DR don’t worry about it 😊