I read these complaints so was surprised to have a different experience.

We’re based in the UK and cancelled via the website because there was no option for us to cancel via the Apple TV app (probably signed up on my laptop originally, I’d guess), and there was a comment field so I did not hold back in informing them exactly why I was cancelling.

So I wonder if the availability of the comment field varies by country or sign-up method - not that there’s any really good reason it should do.