anyway i think there is an addon that does something like that https ://www.curseforge.com/wow/addons/global-ignore-list although you might have to find it elsewhere to get it for classic.
idk how it does it or if it works but they claim it does. in any case it also lets you ignore more people and set notes for them so its worth having either way
tbh I’m mostly looking for something that would let me see messages from ignored players in group chat, or at least warn me when a group member is on my ignore list.
Also, it would be nice if there was a way to prevent friendly players from healing, buffing, and/or dispelling you, but that can’t be done with addons.