This seems to be changing, in the year of heavy LLM use that I’ve done.

When I started, I had to review every line, and frequently found bugs, but lately, I’ve been impressed with the quality of the code. I don’t think that I’ve had to make any code-level adjustments, in a while.

Do you have any analytic basis to make that assertion? I haven't found that to be true, it'd be more accurate in my experience to say that LLM code has different issues than the code humans write.

Six months ago this ceased to be the case for some (if not most), and the quality of LLM generated code has increased over time.

I'm sorry to be the bearer of bad news: human coding has not improved a lick since then.