Skipped" Junior--how to catch up/deal with imposter syndrome

I recently finished my MSE in computer science. I had a return offer from an internship to be a Junior Software Engineer, but since it started in May I kept applying to see what was out there. My frie

I recently finished my MSE in computer science. I had a return offer from an internship to be a Junior Software Engineer, but since it started in May I kept applying to see what was out there. My friend who is a Senior SWE at a "better" company helped me by referring me to hiring managers for junior positions he saw open. We then learned that the company will hire only undergraduates--mostly returning interns--for SWE I. With an MS, HR considered me "experienced." Long-story short, I ended up getting hired as an L4 and placed after team matching. I can tell I will learn a lot here, but I am struggling. One week in, I was carrying the same point load and complex stories as my teammates. There are tons of tools and platforms I don't know (Redux, Kubernetes, Kafka, and Cassandra are just a few), but there is really no ramp-up. I am ashamed to say that for a couple of stories, I worked with Claude but didn't fully understand the code I was writing. I feel guilty because my manager was supposed to get a mid-level engineer, but she really got a junior. Is there a way I can self-advocate and keep up without "outing" myself or dragging the team down? I cry probably 1-2 times a week because I feel frustrated and helpless. How do you deal with imposter syndrome in these situations?