One thing I'd love to see in editors is some indication of a comment's age related to the surrounding code.

More often than not, when a comment doesn't align with what surrounds it is due to it predating the code and it never having been updated.

Anyone seen anything like this?

@djm Git blame can dim code by age, I would guess some editors have that capability too. I have also seen plugins that show blame info when your cursor is on the line. Showing this for comments specifically would indeed be useful.
@adamchainz Bingo! GitLens on VSCode has this feature but it's opt-in. Ty!