I have a whole raw chicken I’m about to roast, and I noticed grey streaks on the fascia under the skin. What is it, and is it ok to eat?

As a rule, grey in poultry is a sign your bird is not good for eating. But if these strips are showing up on the surface of the breast meat, and look more whitish that grey, it doesn't mean your bird is for the garbage. In that case, the bird had a muscular problem known as woody breast. It does affect the taste and texture to some extent, but nutrition wise and safety wise, it doesn't. If your bird has been hanging out in the fridge for a few days, or on the counter to thaw- then it may be bad. I'm assuming it smells like a normal raw chicken, and isn't sticky or otherwise giving you ideas it may be past the consuming date.

I have seen that, too. I think they are minute veins. After it is cooked, you don’t see them.