As a Scrum Master, as defined in the Scrum Guide, you are supposed to do different things.
Of course, you must read carefully the Scrum Guide and deeply understand the framework. This is really a lot, more than many people do. But to be honest is not enough.
According to the Guide you are, for example, supposed to facilitate Scrum events. Do you understand what is the theory and techniques behind it? Have you, apart from facilitating yourself, studied and been trained for it?
You are supposed to help the Development Team to create high-value products. How much do you know about business? How about the technical aspects of what the Development Team is doing, do you know what they talk about?
When working with the organization on teaching Scrum and Agile principles. How much do you know about teaching, public speaking, negotiation, and many other aspects implied in communication?
What I insinuate here can be uncomfortable and challenging, yes.
I talk about the same level of mastery we should promote all around the teams. Don't think you already know everything you need just because you have been doing it for some time. This can be the most painful part. It is not just about Agile but human mind. Accepting all that we really know that don't know.
As Epictetus said:
It is impossible for a man to learn what he thinks he already knows.