I'm currently working closer to the product side (i.e. consumer-facing) on my team. However, I want to move deeper into the infra layer, more into the back-end and away from the front-end, as that's what I'm more passionate about and this area should be more technically complex.
I've brought this up with my manager a couple times, but they said that since I'm already doing great in my current role, they would prefer for me to stay here. How can I navigate this conversation and convince them of this move?
Like with all situations, it's important to have empathy, and in this scenario, it's understanding your manager.
Putting myself in your manager's shoes, I think their priority is maintaining the stability of the system. It looks like you are a very accomplished senior engineer, so they have some reservations around stability loss if you were to move off and leave a gap.
All that being said, I think the main thing to do here is a crucial senior engineer behavior: Make yourself replaceable. Here are my thoughts here:
As a senior engineer/tech lead, it's crucial to learn how to work through others. I did this a lot at Meta and Robinhood, and this allowed me to move around pretty freely and work on what I wanted. I hope you're able to find the same cadence eventually!