Why do some Japanese people generalize other races like, “中国人って…(insert negative thing)”?

But meanwhile freely generalize Japanese people like "日本人は…(insert positive thing)". I don't think it's bad to feel pride and unity for your own country; every country does that. It's like going "We Brazilians love…" or "We Brits prefer to…". Having said that, I don't really see people from other countries generalize other countries negatively and for it to just be considered no big deal. I don't even work for a big company and from time to time I'll straight up hear things like, "中国人嫌い", "中国人って品がない", "中国人って喋るのうるさい". Like all I say back is "ああ…そうなんですね…" to avoid confrontation, but inside my head I'm thinking that's kinda racist.." So, Is it just me hearing these things, or is this a common occurrence here? Sorry, I just had to get this off my chest.