Is there any update on this bug?
The current behavior is unacceptable when the SVG color
is supposed to be the same as some color in Emacs
(in my case, I’m using SVG to build some UI elements),
The following code

(require 'svg)

(defun make-image (color)
  (let ((svg (svg-create 100 100)))
    (svg-rectangle svg 0 0 100 100 :fill color)
    (svg-image svg)))

(set-frame-parameter (window-frame) 'background-color “#f00000")

(insert (propertize " " 'display (make-image "#f00000")))

produce very notable color difference.