What is the ruling on swallowing saliva while bleeding from the mouth during fasting, knowing that it may continue for a period, and what is the ruling on swallowing what has mixed with blood of a yellowish fluid that has no taste?

If the reality is as you described, then you should strive to get rid of the blood mixed with saliva by rinsing your mouth, and be careful not to swallow any of it. As for the remaining small yellowish traces in the saliva, there is no blame upon you for them, and your fast is valid, Allah willing.