الشَّهِيدُ: مَنْ قَتَلَهُ الْمُشْرِكُونَ،
Translation: A martyr, in the legal definition here, includes one killed by the opposing polytheist combatants,
This concerns the classical legal category of battlefield martyrdom and does not classify every form of killing.
The cause and circumstances of death matter. The discussion determines funeral rulings, not authority for private violence.