If a stub template includes an image size declaration that includes "px" then that image is shown at native resolution in the editor.
This was observed with [[Template:Cornwall-stub]] which originally had the code:
{{asbox
| image = Flag of Cornwall.svg |
| pix = 30px |
| subject = [[Cornwall]] |
| category = Cornwall stubs |
| name = Template:Cornwall-stub |
}}
When the "pix" parameter was changed to just "30" [https://en.wikipedia.org/w/index.php?title=Template:Cornwall-stub&diff=564819917&oldid=547286019] as was used by e.g. [[Template:Nigeria-stub]] the image size was displayed correctly. The icon has been rendering at correct size when rendered for reading, presumably since [https://en.wikipedia.org/w/index.php?title=Template:Cornwall-stub&diff=next&oldid=235904748 2009].
Interestingly it renders as intended in VE when the template is initially placed, but does on every subsequent time it's opened in VE.
Feel free to use [[User:Thryduulf/stubtemplate]] for testing (I'll leave it up at least until this bug is closed) as I have altered the actual Cornwall-stub template.
Version: unspecified
Severity: normal
See Also:
https://bugzilla.wikimedia.org/show_bug.cgi?id=51826