Some really good advice on here.
A task for you:
Think of a manager, a really good one, you’ve either reported to or seen in action, what did they do that you liked? List down everything you observed / felt as a subordinate.
Think of a really crap manager, list down everything that you observed / felt.
We have leadership behaviours in our workplace which are really simple behaviours (and are linked to management development training I do which includes the questions above).
Leadership is a skill that gets better with time, experience of things going wrong / right, challenges, on the job training and formal training (tiny part).
The “feels” of good leadership are really interesting to study. Feeling like you have autonomy but someone to catch you if you slip up. Someone to push you out of your comfort zone but give feedback to you so you can improve.
You should definitely speak to your new line manager about how you’re feeling. They should, if they are a good leader, help you work on your development areas as a leader, so that you don’t feel “imposter syndrome”. The very fact you are being reflective, says to me that you are already a good leader and just want to be better. Discuss it with your manager or HR.