You don't need to know everything
As your product supports more features and your infrastructure becomes more complex, there’s a point in time where you won’t know everything anymore – and that’s ok.
What matters is that you know the system you own in great detail and know adjacent components at a high level (and how they interact with your system). This is what’s sometimes described as a T shaped engineer (deep knowledge of one system and shallow knowledge of other systems).
With that being said, it’s still ok even if you don’t know the answer of the system you own. If that happens, keep ownership of your system and just answer that you don’t know but will figure out – and then promptly circle back to the person with their answer. Ownership is about figuring out the answers rather than knowing all of them on top of your head.
Being aware that people’s knowledge is usually in that T shape may also help if you are struggling with imposter syndrome – it may seem that other peers know a lot more than you, but they also don’t know much about your field of expertise. As long as you keep an open mind and keep learning, you will keep growing.