I'm not GP, but I've been experiencing this too. All my coworkers are in the same boat though, so we don't really have anyone with the deep understanding. Our approach (which has been working pretty well, we've solved a lot of problems and learned some along the way) has been to use AI as an informer who also points us to sources (like documentation, github issues, etc) where we can then read up on something the AI has pointed us at. We try to time box things a bit to prevent going down the rabbit hole, so we don't always get to exhaust our curiosity, but we're continually gaining that knowledge and pressing forward. Most recent example is tuning the kernel settings and our app on our prod machines to behave better for WebRTC packet handling/forwarding. AI for things like ffmpeg has been a god send when nobody on the team is an ffmpeg expert.

I've also had success just asking claude to write documentation on a system or subsystem or module, etc, and reading that. I then sometimes have it turn that into an svg diagram or something visual that often helps understand things. That domain-specific knowledge is hard to gain though, so not a silver bullet by any stretch.