As an additional point; “weird” isn’t a slur. A slur is an expression where the very words themselves are considered obscene - a slur is offensive, even when it is used to describe someone or something according to its strict definition.

There is no context where describing someone as a “removed” or a “retard” isn’t offensive. “Weird” isn’t like that, as you’ve pointed out - it’s being used as a simple insult, and it’s persistent because it seems to really annoy the people it is directed at