Can you not collapse them at all or do you mean that they uncollapse after a refresh?

The latter might have to do with HN storing this collapse-state in a Cookie/localstorage/similar and Firefox Focus throwing these sorts of things semi-regularly away to protect privacy.

It does not throw away the login-Cookie, so I'm not entirely sure how it works. They might even have a whitelist or (in this case erroneous) blacklist for it.

It doesn't display the button.

Really not sure then. Maybe try toggling some of the tracker blocking in the settings and see if that changes anything.

It does show the button for me on the Android version...

I find the hit target really small on regular Android Firefox too. It often takes me multiple attempts to get comments to collapse.

are you blocking javascript? hn is very good about not needing it for the site to function basically, but i think collapsing comments is one of few things it needs it for.

Don't think you can block JavaScript with Firefox Focus (which is a different browser from Firefox).

At least, I can't do it on the Android version. The iOS version might be different...

Not blocking javascript.