9 years and you consider yourself a „senior” and you still think about how you „feel” left behind? What do you expect? Processes take time - all of them. I ventured into a new domain 3 years ago and got comfortable within one year. Then found out I know nothing around year two. Then again. Back and forth. True seniors, experts, whatever you call them - they don’t get comfortable.
To clarify, sometimes I get the sense that the sort of people, also like myself, who come on here, have this delusion that this tech stuff will cheat reality. That you do this and that, you play your cards well and you will skip ahead of everyone else in all the other professions in society. A sort of technocratic megalomania.
I absolutely do not know that the OP is like this. My experience „switching” domains is that it can help to find the common familiar denominators with what you know in the new thing. And then, like an anthropologist, to develop a respectful understanding of the people who are experts in this domain. You keep it respectful by recognizing that you’re not going to catch up with them. It’ll be their job to convey to you what their problems are, and yours to listen carefully. You might be good with that hammer you’re holding from your earlier experiences, but they might not even have nails for you to bang on. That’s where the discomfort comes in.