[bombolo]

Both… and version jumps in formatting tool basically will touch every single file.

[makapuf]

Every file that changed because rules changed, which shouldn't be frequent, I don't remember black changed radically since its creation, do you have an example of some widespread syntax change ?

[bombolo]

Just take a codebase and run black from different ubuntu releases.

The funny thing is that if you run the versions backwards you will NOT obtain identical files with what you started with.