With \DocumentMetadata{} and the luacolor package, the URL link color turns black. See the following code. Remove \DocumentMetadata{} and the link color is blue as specified. I always use the luacolor package with luatex to fix the spacing problem of xcolor.
\DocumentMetadata{} %-> Link color -> black
\documentclass{article}
\usepackage[colorlinks=true,urlcolor=blue]{hyperref}
%\usepackage{xcolor}
\usepackage{luacolor} % fix xcolor's spacing problem.
\begin{document}
\url{https://en.wikipedia.org/wiki/Durbin–Watson\_statistic}
\end{document}
With
\DocumentMetadata{}and theluacolorpackage, the URL link color turns black. See the following code. Remove\DocumentMetadata{}and the link color is blue as specified. I always use theluacolorpackage with luatex to fix the spacing problem ofxcolor.