Is it obligatory to interrupt the prayer upon feeling the discharge of secretions, which cannot be distinguished between (mani or madhiy) due to intense waswasah regarding purity?

The cure for obsessive doubts (waswas) is to ignore them and not pay them any attention. If you doubt the emission of maniy (sperm/seminal fluid), ghusl (ritual bath) is not required of you unless you have absolute certainty. The description of maniy has been explained in previous fatwas. If you doubt what has exited, then choose and assign it one ruling. If you feel that something that nullifies wudu (ablution) has exited during prayer, and it is merely a doubt or an obsessive whisper, then pay no heed to it and continue your prayer, and do not investigate after the prayer, for the default is that nothing has exited. However, if you are absolutely certain that something has exited, then your prayer is nullified, and you are required to repeat it and perform wudu.