Hi,
I was using \setuppagenumbering[alternative=doublesided] to get double
sided pages.
After doing that I noticed a thin white line on the right side.

Here is a Minimal Working Example:

ConTeXt  ver: 2023.09.26 18:19 LMTX

\setupbackgrounds[page][background=color,backgroundcolor=black]
\setuppagenumbering[alternative=doublesided]

\starttext
a
\stoptext