Please stop embedding files/images from Discord. Discord has anti-hotlinking logic in place that breaks links to Discord hosted files and images when linked to from anywhere outside of Discord. There are a multitude of file/image hosting sites you can use instead.
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It's not being rude at all, in fact, quite the opposite.
He could just ban someone without giving reason or warning them of what they've been doing wrong. If he didn't do that, would you still consider him "rude", because of him warning others of what they've done wrong?
When I was banned, I knew exactly what I did wrong, and tried my best to fix it. But I only knew what I had done wrong because of the warnings and infractions given to me beforehand. Without that, I wouldn't have improved to how I am today, and I'd most likely have been permabanned by now.