It's not just docstrings but also triple-quoted strings in general.

CI passed on the initial formatting PR, so I think it was able to format triple strings (minus docstrings)

I think whatever it does do with triple-quoted strings interacts badly with merges.

I think whatever it does do with triple-quoted strings interacts badly with merges.

I’m pretty sure this wasn’t the problem with your PR. I’m pretty sure the problem was that the first instruction to format each of your commits before the rebase didn’t actually format them as expected.