TT points to the general prohibition of blood (of bird and beast) and the karet attached to it.
וכל דם לא תאכלו בכל מושבותיכם לעוף ולבהמה — איסור דם עוף ובהמה בכל מקום. כל נפש אשר תאכל כל דם ונכרתה הנפש ההיא מעמיה — כרת על אכילת דם.
“And you shall not eat any blood in any of your dwellings, whether of fowl or of beast. Any person who eats any blood, that soul shall be cut off from its people” — the prohibition of the blood of bird and beast applies in every place, and eating it incurs karet.
Custom — primary negative commandment with karet.
It is forbidden to eat the blood of a bird or beast anywhere; the penalty is karet.