Expectations as a new grad

In order of priority:

• First and foremost, focus on the successful delivery of your project.
• Second, focus on a positive working relationship with the senior engineer.
• Third, focus on your learning.

These priorities don't have to be in tension with each other. In fact, the best work you can do is the intersection of all 3 priorities above.

Especially since you'll be going on leave in a month (that's something which is presumably your choice, not the company's choice), you should really focus on the first two. As you earn more trust and become faster in your own job, you'll have more ability to decide what to work on.

In this project, you mention:

however my senior engineer has started work on these and it looks like most of the work I'll do is reviewing/testing her PRs.

There's still a ton of learning potential here.

• You can do a very thorough job reading and testing the frontend code
• You can proactively identify bugs or minor improvements as your senior is writing the code, and put out a code change to help her
• You can understand what tools or best practices are being used by other teams in the company, and apply that in this project
• You can propose new ideas or ask smart questions

So my recommendation:

• Don't "complain" to your manager that you're not working on the tech that you want to work on. I know you would frame the discussion in a better way, but there's still a risk that you come across as needy or selfish.
• Focus on making your contribution to the project rock-solid
• Be very helpful to the senior engineer, even more than she expects

Our deadline is in a month, as I'll be going on leave. I wanted to do a portion of the FE just to learn more about frontend technologies and was assigned tickets, however my senior engineer has started work on these and it looks like most of the work I'm going to be doing, apart from my tasks, are going to be reviewing/testing my senior engineer's PRs. I've worked with this part of the product before but I was hoping to get more exposure and practice.

I would chat with them to see if you can help them with the frontend work. If they are more senior doing FE, there's probably some work they are doing that they've done a thousand times. Those tasks will be a good match for you because:

1. They'll be able to support you through the task if you need it
2. They'll be able to work on something that pushes their limits a little bit more
3. The task will still be novel to you where you'll be learning