Light foam on stock

Tried a new recipe for chicken stock and this very light foam is rising to the top that doesn’t seem like scum, not too sure. Any tips and constructive criticism is also appreciated :)

Recipe; Whole chicken carcass roasted for 45min at 550 degrees mirepoix and garlic bulb roasted at 400 with bones for around 20 minutes Half a can of tomatoe paste and a cup of white wine for deglazing pan Added 3 bay leaves, and a handful of parsley, thyme, and rosemary