Hello, 👋🏽
It seems there is an issue with inputboxes inserted within a template. The inputbox does not read the values passed as parameters ({{{1}}}, {{{2}}}, etc.); instead, it treats them as string literals.

To reproduce the problem, you can follow these steps:
Go to the English Wikipedia (enwiki).
Navigate to the page: User:Super nabla/C.
On that page, you will find an inputbox labelled "click here."

What happens?:
Clicking on the inputbox, a new page titled "Editing Wikipedia:Sandbox (new section)" opens.
The preloaded text is: "Hello {{{1}}} {{{2}}} {{{3}}} {{{4}}} world!"

What should have happened instead?:
The preloaded text should have been: "Hello one two three four world!"
(because "one", "two", "three", and "four" are the actual values passed to the template call)

Software version (skip for WMF-hosted wikis like Wikipedia):
(skipped)

Other information (browser name/version, screenshots, etc.):
Firefox Browser 123.0.1 (64-bit)