This is the exact same feeling I got when I was coding things before AI. There's a meme we had at the office where someone runs git blame on the shitty code and realizes they wrote it. We tried to have people do tech talks about the hardest things they had to build, but most people don't even remember it after 6 months.
I think when people are in flow, they act possessed. It's not even muscle memory forgetting. They make the same mistake. They add a line that fixes Bug A but causes Bug B. They then remove the line causing Bug B, and Bug A regresses. Then they'll scratch their heads wondering why Bug A is still there.
I have the opposite experience with vibe coding. I know where the models are. I know what's in the DB, the tables, every migration, even though I focus on FE. I can tell AI where the files are, before it loads the first prompt.
I know when it's creating memory leaks, whereas I usually miss my own leaks because I'm in the code and forget obvious things like destroying a thread or coroutines running in the wrong space.