> It means that I take something from culture X and pretend that it is from my culture

That’s literally how new things came to be in every larger culture. Sushi didn’t magically come into existence across all of Japan simultaneously. Rice techniques were continually improved upon and exchanged throughout the hundreds of cultures across Asia.

> Sushi didn’t magically come into existence across all of Japan simultaneously.

Welp. It didn't even originate in Japan specifically.

https://en.wikipedia.org/wiki/History_of_sushi

Exactly my point. Most things gradually get incorporated into a larger culture, like yoga.

If I take yoga, and call it something else without actually changing the fundamentals and say it is superior, that’s appropriation.

Nope, it’s called appropriation even if you credit the original culture and keep the same name: https://en.wikipedia.org/wiki/Cultural_appropriation

A restaurant was protested for cultural appropriation because the owner was white and it was serving Sonoran recipes under the original name. It was just the fact that a white person was profiting off of that particular subculture that made it appropriation.

So... you literally just described "progress" throughout all of human history. The Greeks and Roman are a good example of that. The entire back and forth history of the Silk Road (the real one). Even the Crusades had cultural dumps back and forth. Um, Japan is also considered the modern day "Rome" when it comes to taking other inventions and improving on it beyond their creator's imaginations. Like, are we going to yell cultural appropriation against the Japanese for building the Mitsubishi Zero (I don't know enough about sushi to talk about it beyond the california roll being a fucking abomination)? They didn't invent the airplane, but I dare you to find a history nut who isn't going to talk kindly about the engineering and general marvel that plane was for its time, along with how it forced the USA to adapt their learning and counter maneuvers to combat it. It was a super important plane to both military and aviation history, even though it's technically a piece of cultural appropriation.

Ever think the whole thing is just making a mountain out of a mole hill since it's never the "offended culture" that's ever offended, but some random person in San Fran or Los Angeles without a real job?

You take it into to far wide a scope. It is something that is, for the most part a modern notion in the context of taking from somebodies culture and presenting it either as yours to show your cultural superiority, and obfuscating in some cases the origin. Basically it’s the same as if copied your shiny new app you worked on and declaring I made it, or invented it. I am appropriating your work as mine.

I think your scope is too narrow.

Consider white girls at music festivals wearing bindis as a fashion statement. I don't think this fits your definition, but it is a popular example of cultural appropriation.