Is it permissible to swallow blood after a lip injury, taking into consideration a fatwa that permits this outside of Ramadan but forbids it during Ramadan?

It is not permissible for a Muslim to swallow blood, whether a little or a lot, in Ramadan or otherwise, because it is forbidden by the text of the Quran: "He has only forbidden to you dead animals and blood," unless he swallows it forgetfully or involuntarily, in which case there is no sin upon him. As for blood coming out of the mouth after ablution, it does not invalidate it.