"--color-moved" ignored in "git diff --word-diff=porcelain --color-moved"

using git 2.28.0, and when doing >>>git diff --color-moved
--word-diff=porcelain lines.txt<<<
the --color-moved argument seems to be completely ignored, and seems
there's no way to differentiate moved lines from added/deleted lines
in the output, is that intended? if the 2 arguments are incompatible,
wouldn't it be better to throw an error? or at least print a warning
in stderr? instead of just ignoring one of the arguments?