This is a very minor point in the scheme of what went on, but I’ve seen flags. Unless they are made out of cotton, most flags would not ‘soak up’ blood. Of course, I don’t know what kind of flag was there, but of all the flags I’ve ever seen, they are not absorbent (usually, they are polyester or nylon), which makes me wonder how much blood was really there.
I have seen a number of people receive gunshot wounds, mostly from rifles. Sometimes there is a lot of blood. Sometimes hardly any escapes the body.