Size feature + variable fonts = unexpected output

[Keks-Dose]

https://tex.stackexchange.com/questions/729880/size-features-for-variable-fonts-have-non-consistent-output

MWE:

\DocumentMetadata{lang=de}
\documentclass[parskip=half, ngerman, fontsize=12pt, paper=A5, DIV=25]{scrartcl}
\usepackage{babel}
\usepackage{fontspec}

% \setsansfont{Alegreya Sans Regular}[
% Renderer = HarfBuzz,
% SizeFeatures = {
%   {Size = -11, OpticalSize = 16, Color=AA0000},
%   {Size=11-13, OpticalSize=36, Color=00AA00},    
%   {Size=13-, OpticalSize=72, Color=0000AA}},
% BoldFont=Alegreya Sans Bold,
% ItalicFont=Alegreya Sans Italic,
% BoldItalicFont=Alegreya Sans BoldItalic,
% BoldFeatures = {
%   SizeFeatures = {
%   {Size = -11, OpticalSize = 16, Color=AA0000},
%   {Size=11-13, OpticalSize=36, Color=00AA00},    
%   {Size=13-, OpticalSize=72, Color=0000AA}},
%   }
%     ]

\setsansfont{FrauncesVariable.ttf}[
%Renderer = HarfBuzz,
SizeFeatures = {
  {Size = -11, OpticalSize = 16, Color=AA0000},
  {Size=11-13, OpticalSize=36, Color=00AA00},    
  {Size=13-, OpticalSize=72, Color=0000AA}},
BoldFont = *,
ItalicFont = FrauncesItalicVariable.ttf,
BoldItalicFont = FrauncesItalicVariable.ttf, 
UprightFeatures = {Weight = 300},
ItalicFeatures = {Weight = 300},
BoldFeatures = {Weight = 600},
BoldItalicFeatures = {Weight = 600},
]

\renewcommand{\familydefault}{\sfdefault}

\title{Fraunces}

\newcommand{\blindsatz}{Lorem ipsum dolor sit amet, consectetuer
  adipiscing elit. Etiam lobortis facilisis sem. Nullam nec mi et neque
  pharetra sollicitudin. Praesent imperdiet mi nec ante. Donec
  ullamcorper, felis non sodales commodo,}



\begin{document}
\maketitle{}



1234567890

\blindsatz{}\footnote{\blindsatz{}}

\emph{\blindsatz{} 1234567890}

\textbf{\blindsatz{}}

\textbf{\emph{\blindsatz{}}}

\end{document}
% Local Variables:
% TeX-engine: Lua-dev
% End:

The italic paragraph is green, despite there is no size + color command for the italic. 
![241031-Fraunces-Variable](https://github.com/user-attachments/assets/76eed7e2-20c1-4279-8465-f4f54ae0a703)

Works with Alegreya Sans as expected. I used Fraunces, because it is mentioned in the luaotfload manual.

[zauguin]

Personally I would have expected the SizeCommands to be inherited by other styles and am more surprised that bold italic is not showing up in green, but in any case luaotfload is working as expected here and rendering exactly what is requested by fontspec. Moving to fontspec to figure out what the intended behavior is and if it fits what's currently happening.