The new ULS-based language selection dropdown is shown partially offscreen when page is in RTL language.
- Visit https://commons.wikimedia.org/wiki/Special:UploadWizard?uselang=ar
- Work through the form to the last stage ("Describe")
- Click the dropdown with a language name on it
For comparison, this is how it looks like in LTR.
Looks like the logic for displaying the popup does not flip it for RTL (it is aligned to the left edge of the dropdown, rather than the "start" edge).