Not exceeding expectations in Performance Review

I am a mid level data engineer with 3 years of relevant experience, been working with the current company for 1 year. My manager said I only meet expectations in my performance review. I was surprised that I didn’t exceed expectations as I had a large scope this past year. I asked her and she said I have the scope of a senior but still can’t fully explain every concept / feature I worked end to end. There’s so much to learn / do that i don’t have enough time in a workweek to explain everything yet. How long does it take to explain every concept E2E? How many people exceed expectations for performance review?