Steps to replicate the issue:
Presumably the replication steps are:
- Set https://en.wikivoyage.org/wiki/Special:Preferences#mw-prefsection-rendering-files to 120px
- Edit an article (e.g., add an image)
- Post your changes, and see the images in the wrong size.
What happens?:
The image previews at 120px but when the page is saved/published, it displays at the site's default size.