The computed font-size on that input is 14px. It must be at least 16px for iOS to not zoom in.

We had problems in VE where iOS zoomed in even though the font-size was 16px when focusing a content-editable element, but I don't think this is the case here.

This is not an OOUI bug. The reduced font size is set on .rcfilters-container and on .mw-rcfilters-ui-overlay.

@Jdlrobson @ovasileva sounds like Readers web plans to work on this so I'm marking as external, but let us know if that's not the case.

Setting this as a small for now, if the quick fix approach doesn't work, we should flag that and discuss next steps

Change 533361 had a related patch set uploaded (by Nray; owner: Nray):
[mediawiki/core@master] Fix iOS input text zoom bug on rcfilters input

https://gerrit.wikimedia.org/r/533361

I made a quick attempt at this (the suggested quickfix) although I can't reproduce the problem on my iPhone iOS 12

Change 533361 abandoned by Nray:
Fix iOS input text zoom bug on rcfilters input

https://gerrit.wikimedia.org/r/533361

Moving this back to to needs analysis as the quick fix I tried in core was controversial. We can try to quickfix in either MF or Minerva, but I'm not sure where to put it? Since it is mobile specific, I would guess MF but is there a good place in MF for this rn without creating another module? @Jdlrobson

The patch wasn't controversial. I think James was trying to say is that it didn't belong in core. Add a skinStyle for the mediawiki.rcfilters module in Minerva or even better add a rule

textarea: { font-size: 1em; }

to Minerva. Currently we default to 11px.

Change 533937 had a related patch set uploaded (by Nray; owner: Nray):
[mediawiki/skins/MinervaNeue@master] 🐛 Bug: Fix iOS input text zoom bug on rcfilters input

https://gerrit.wikimedia.org/r/533937

In T231049#5455437, @Jdlrobson wrote:

The patch wasn't controversial. I think James was trying to say is that it didn't belong in core. Add a skinStyle for the mediawiki.rcfilters module in Minerva or even better add a rule

textarea: { font-size: 1em; }

to Minerva. Currently we default to 11px.

Because the parent element of the text input has font-size: 0.875em, we unfortunately can't just set the text input to have font-size: 1em because it wouldn't change the computed font-size. I've made a patch at https://gerrit.wikimedia.org/r/#/c/mediawiki/skins/MinervaNeue/+/533937/ that sets the text input's font-size to 16px, but this introduces new problems (users who change their browser font-size won't notice a change with that element). Anyways, I'm not sure if that patch is an actual improvement because of this but I think it will fix this bug.

Edit: I changed the patch to just use rem units. For browsers that don't support this, it should just fallback to the inherited font size

Change 533937 merged by jenkins-bot:
[mediawiki/skins/MinervaNeue@master] 🐛 Bug: Fix iOS input text zoom bug on rcfilters input

https://gerrit.wikimedia.org/r/533937

@alexhollender I'm not sure if you'd be interested in reviewing this or not, but if you are, you can see the changes on https://en.m.wikipedia.beta.wmflabs.org/wiki/Special:RecentChanges?hidebots=1&hidecategorization=1&limit=50&days=7&enhanced=1&damaging__likelygood_color=c2&urlversion=2

The font-size of the text input box (the one with "Describe the purpose of the filter" placeholder text) was adjusted a little so that the zooming wouldn't happen