Today the Discussion Tools arrived on plwiki (and perhaps other wikis). It uses the same layout as on the desktop to display the [subscribe] and [cancel subscription] buttons. However, this makes headers very narrow as button takes around 50% of the screen width. What's more it's a button on a button, since by default headers on mobile are clickable.
A screenshot is available here: https://imgur.com/a/JS7HNNX
https://pl.m.wikipedia.org/wiki/Wikipedia:Kawiarenka/Kwestie_techniczne