Will I be sinful if I agree with one team to lose a match in exchange for another team winning, whether the agreement is verbal or telepathic, knowing that the team's losses are deliberate?

This type of hypothetical question is unrealistic and may not occur. We have previously clarified in earlier fatwas the invalidity of telepathy and communication through spirits.

It is better to occupy oneself with Islamic knowledge, studying the texts of revelation and the works of scholars, as this is superior to preoccupation with hypotheticals. The Salaf condemned excessive questioning about intricate, strange, or unoccurred matters. The Companions used to ask the Prophet, peace and blessings be upon him, about real-life matters that would benefit them, not about hypothetical scenarios or difficult problems.

Many of the Companions and Tabi'in disliked asking about events before they occurred. What is required of a Muslim is to focus on what has come from Allah and His Messenger, to understand it, then to believe in it or act upon what is contained therein, and to abandon intellectual questions and theoretical possibilities.