Tabularray checks at the start of the document if the xcolor package is loaded and if yes it will automatically load the ninecolors package, which (amongst others) defines azure3.

Here the relevant part of the tabularray source:

\AtBeginDocument{ \@ifpackageloaded{xcolor}{\RequirePackage{ninecolors}}{} \@ifpackageloaded{hyperref}{ \newenvironment{tblrNoHyper}{\NoHyper}{\endNoHyper} }{ \newenvironment{tblrNoHyper}{}{} } } 

Tabularray checks at the start of the document if the xcolor package is loaded and if yes it will automatically load the ninecolors package, which defines azure3 (amongst others).

According to the tabularray documentation, this is done for proper color contrast.

Here the relevant part of the tabularray source:

\AtBeginDocument{ \@ifpackageloaded{xcolor}{\RequirePackage{ninecolors}}{} \@ifpackageloaded{hyperref}{ \newenvironment{tblrNoHyper}{\NoHyper}{\endNoHyper} }{ \newenvironment{tblrNoHyper}{}{} } }