DOCTYPE svg is being reported as suspicious

[Firzenizer]

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
<svg width="100%" height="100%" viewBox="0 0 3988 855" version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" xml:space="preserve" xmlns:serif="http://www.serif.com/" style="fill-rule:evenodd;clip-rule:evenodd;stroke-linejoin:round;stroke-miterlimit:2;">
    <g transform="matrix(4.16667,0,0,4.16667,0,0)">
		XXX
    </g>
    <defs>
        <linearGradient XXX/></linearGradient>
    </defs>
</svg>

DOCTYPE svg tag is being reported as suspicious is there some reason for that?