Does a fasting person break their fast if something comes up from the stomach and reaches the throat, and then they involuntarily swallow it?

Your fast is valid as long as you swallowed what you mentioned unintentionally, out of forgetfulness, or because you were unable to expel it, based on the statement of the Prophet, peace and blessings be upon him: "If someone forgets and eats or drinks, let him complete his fast, for it was Allah who fed him and gave him drink." The fasting person should be cautious of things that invalidate the fast.