Stefan Kangas <stefan@marxist.se> writes:

>> As for foreground: what does it mean to remove the foreground from an
>> image?

(I realize that I didn't answer this part in my previous reply.)  SVG is
a special case, where we just use the foreground of the current face.

In this case, I think the fix is as simple as the attached patch.  I've
tested this with several themes, and it looks very good to my eyes.

I suggest that we install this fix on emacs-28.