While there could be many causes for the bleeding of the nose in a snake, one of the most common reasons in captivity snakes can have a nose bleed is because the snake is rubbing their nose and face against the enclosure wall for extended periods. This is likely due to the snake lacking something in its environment and is trying to escape its enclosure.
If an animal is consistently trying to leave its enclosure, it means they are unhappy with the environment and are looking to escape. Perhaps this may be due to dehydration, too much or little light, issues with the substrate, air ventilation, places to hide, the temperature, and or humidity, etc. Also, snakes are known to attack the glass because they feel threatened when they see their people or movement in general; this behavior long term can cause damage to the face, such as bleeding of the nose.
This problem is severe, especially if the animal’s nose is already bleeding, as bleeding usually occurs only after an extended period of rubbing or signifcant damage. This dissatisfaction can lead to anxiety, or the wound may get infected, ultimately killing the animal. The solution to this problem is to discover the source(s) of this desire to leave the enclosure and address it. Continue to experiment and try to find why this is happening until the animal is at peace.
If there are no signs of nose rubbing on the snake’s face, but the snake’s nose is still bleeding, it could be an internal problem, and most likely has a medical cause. Perhaps it could be caused by a disease, parasite, or bacterial infection, although I am not aware of any medical issues that can cause this kind of bleeding. We encourage you to research and explore your options, and if needed, consult a veterinarian to advise you on further action.