Started my 1st FTE SWE job and been on my team for just a few weeks - What should I do?

Here are the main things you should do:

1. Work with your manager to create an expectations plan for your next 3-6 months - The goal is to figure out what it takes to get at least the average rating. If you haven't already, I recommend checking out our full session on performance review: [Masterclass] How To Navigate Your Performance Review In Tech. If you're short on time, just the first half should be enough - You don't need to worry about writing feedback yet. From what you've shared so far, your manager seems to be good, so they should totally understand this request.
2. Ask a ton of great questions - You are new to the team, the company, and your career. You have a sort of "shield" that allows you to really put yourself out there requesting help - It's what everyone will expect of you! To learn about more this, check out this related Q&A pair from an onboarding Twitter engineer: "How can I bridge my confidence gap to put myself out there more and ask for help more aggressively?"
3. Find a person to ELI5 the codebase to you - For a massive tech company like Google with a very custom tech stack, you can't online tutorial your way to a solid codebase understanding. Reading the docs is also risky as docs are rarely properly maintained. Get someone to give you a high-level overview of the codebase and move on to the next action item. Don't know who to ask? Well, you know how to blame code, use that skill! If that doesn't work (maybe the main author left the company), ask your manager for a point of contact.
4. Find small wins to familiarize yourself with the workflow - You want the code contribution process to feel like clockwork/muscle memory to you. The entire process of making a new branch, writing a commit, submitting a change request, going through code review, and then landing it - It should feel like breathing to you after 1-2 months. I talk more about this here: "What kind of tasks should I work on as an onboarding engineer?"

To go super deep into all of this, take this course: The Complete Onboarding Guide For Software Engineers

For the longer term, the key to really solidifying yourself as a strong L3 engineer and making progress to L4 is to champion stellar code quality. You can learn more about that from this course: Level Up Your Code Quality As A Software Engineer

Start being productive as soon as possible! “Productive” could mean a lot of things, so start small. A few ways to have immediate impact (within the first week or 2):

• Ask questions about the onboarding guides. There will almost certainly be issues, or at least ways to improve them, so propose changes and then actually make them.
• Ask questions about the roadmap and how projects relate to one another.
• Identify low-effort changes that are easy to make and undeniably a good thing (e.g. adding a unit test is non-controversial, but refactoring a whole module as a new grad engineer might be dicey)
• Talk to lots of people and ask them what their biggest pain points are, write them down and see if you can find patterns. Share with your manager and see if there’s some low-hanging fruit to improve something.

Ah, I just realized why blaming code is better than blaming people.