How accurate is the warning that "fast prayer kills" and that it entails health risks such as blood clots, concussions, slipped discs, or ruptured neck nerves?

Tranquility (طمأنينة) is an obligatory part of prayer, and it is not permissible to lie or fabricate health crises to frighten someone who abandons tranquility. What was mentioned about the effect of delaying prayer for the sake of eating on health is inaccurate, and doctors should be consulted about it. Delaying prayer until after eating does not contravene the Sunnah; rather, it is in accordance with it if there is sufficient time. Al-Bukhari dedicated a chapter to this, and it was narrated from the Prophet, peace and blessings be upon him, and Ibn 'Umar, that it is permissible for a worshipper to do so until he finishes his food. There is no connection between delaying prayer for food and overeating.