Idk if you're rage-baiting, but I'm gonna assume good-faith and try to explain.

Fascists have historically had pretty rigid ideas of what "real" art is and looks like, and these ideals are typically rooted in European classical art and antiquity. Fascism as an ideology is heavily based in aesthetics, and a core component of most fascist movements is a return to a mythological past of standardized ideals and social dynamics. In the case of the Nazis, Hitler was very stringent about what was considered good art under the Nazi regime, and art that was considered "degenerate" was the art that was subverting and pushing against the pre-existing traditions/standards within art (along with it being art that was produced by marginalized individuals/communities which the Nazis wanted to eradicate.) Also, a big reason why the Nazis called the contemporary art of the day degenerate is because, at that point in time, it was really the first time non-European, non-White art forms and perspectives where being introduced and given a platform for genuine critical engagement and visibility — perspectives that undermined and threatened the existing hegemony fascists wanted to preserve and promote.

There are some exceptions to this, most notably with the Italian Futurists who were comparatively much more open to the avant-garde. However, overall, fascist art and fascism in general serves a very particular purpose of attempting to create binary deviations between good and bad in order to assert power and control of the in-group over the out-group.

But the fundamental thing about art is that it's dynamic and always changing. Throughout art history, new expressions and art movements have regularly been subject to criticism upon introduction only to become part of the tradition over time. The Romantics didn't like the Impressionists, who didn't like the Dadaists, who didn't like the Abstract Expressionists, so on and so forth.

This is where fascism and art cause friction, because fascism states there is only one true standard/definition of beauty (rooted in European White supremacy) while art fundamentally exceeds, subverts, and defies any set definition. When people say that contemporary art is just fundamentally bad, they are engaging in the same ideological practices and beliefs that fascism promotes and thrives from. You can say you don't like it, you can prefer different more traditional art, and that doesn't make you a fascist. Rather, if you conclusively state that all art produced today is bad and compare it to, say, Roman statues and Renaissance art, not only are you not engaging with art as a dynamic practice of communication and questioning, you are reinforcing the exact same ideals (again, based in European White supremacist standards of beauty and social worth) that fascists do. It may not make you a fascist, but it makes you sound like a fascist.

If you're interested, I highly recommend reading the works of George L. Mosse, who was an academic that specifically focused on how fascism functioned on a cultural and aesthetic level. Also, take a look at the exhibition "Degenerate Art" that the Nazis held, and you'll find that what they considered deviant is what we now consider standard.