I don't really understand how they used "brainrot". I thought brain rot was this generations surrealism, a type of art?

By all means, study the detrimental effects of social media and AI on our brains but don't correlate it with people creating art just because.

There are two types of "brainrot" that are related but not the same. Essentially brainrot is anything that is anti-thinking.

The first type of brainrot is what happens when you let other things think for you and your thoughts and opinions become not your own. AI is anti-thinking because you can let the machine think for you. Social media is anti-thinking because you can let other peoples' opinions think for you.

On the other hand, memes actually communicate ideas. For example, The Simpsons Ralph meme "I'm in danger" and the dog on fire "This is fine" memes both represent understanding being in a dangerous situation while doing nothing about it. Star Trek was actually way ahead of its time with the episode "Darmok and Jalad at Tanagra" which was about a culture that used memes as communication.

So what do you get when you combine brainrot ("anti-thinking") with memes? You get brainrot memes, which is the second type of brainrot. For example, 6-7. 6-7 doesn't communicate ideas. It doesn't mean anything. Instead, it communicates the opposite of an idea. So when someone says "6-7", they are embracing using language in an anti-thinking way. In this way, brainrot memes can be thought of more as an anti-meme. It's as contagious as an idea, but since it doesn't contain any information, it acts more like a virus. So brainrot memes are essentially mind-viruses that embrace the lack of thinking that comes with brainrot.