My iPhone doesn't attempt to censor tiananmen square. Typing "tian" into the home screen search bar yields "tiananmen square", "tiana", "tiananmen square massacre", and "tiana musarra".
Maybe the spell checker wanted you to capitalize it? Discord's spell check constantly tells me I've spelled "chicago", "wednesday", and "february" wrong. They're spelled right, but because they're proper nouns, they MUST be capitalized at any cost. It drives me mad.