Probably 3rd party clients that offer quality of life / usability improvements over the website.

E.g. I use Hackers [1][2] because it is much easier to read stories on mobile and supports dark mode. Unfortunately, it doesn't support commenting or downvoting (yet?)

[1] https://apps.apple.com/us/app/hackers-for-hacker-news/id6035... [2] https://github.com/weiran/Hackers