CKEditor not loading on iOS 14/15

The issue summary says there was a change of note in https://github.com/ckeditor/ckeditor5/releases/tag/v42.0.0. Which change is of note?

I installed a site from the 11.x branch on https://simplytest.me but I can't reproduce this bug there. CKEDITOR_VERSION is "42.0.2".

I was referring to the "New installation methods" section, it seemed somewhat relevant as core builds using webpack. My understanding of an upgrade of CKE in drupal is:

1. Update core/package.json
2. cd core
3. yarn install
4. yarn build
5. yarn build:ckeditor5-types

What OS / Browser were you testing with? Here is the same thing (Simplytest default install) showing the issue on 15 with Chrome:

iOS 15 Screen grab →

Safari on iOS 17.6.1.

Because I can't reproduce this on a real actual in-my-hand phone, did you get a chance to try with an un-minified CKEditor? We need the reproduction steps before going on to fix it.

Do you have any idea why that console log comes from user-script.js instead of from Drupal's ckeditor5.js? That could be normal and nothing to do with whatever this bug is.