Have you installed the gnome-themes gnome extensions ? Once installed you can change the theme. Notice that shell theme and app themes are not the same thing. Also, notice that you need to take a gtk theme that supports gtk3 and gtk4 if you are using recent gnome
In a way it’s similar to pseudoscientific alternative therapies people will say it’s awesome and no problem since it helps people, but since it’s based on nothing it actually gives people fake memories and can acerbate disorders